Siluriformes

(Catfishes)

Class Actinopterygii

Order Siluriformes

Number of families 34

Evolution and systematics

The late nineteenth century work of Carl H. Eigenmann and Rosa Smith Eigenmann on South American catfishes established the foundation upon which later researchers, such as William A. Gosline, George S. Myers, and Mario C. C. de Pinna, have built to clarify the classification of catfishes. However, the classification is still uncertain, and there is no full agreement among the authors about the relationships of the families. Most knowledge about the phylogeny of siluriforms comes from the research on Neotropical groups carried out in the last three decades of the twentieth century.

During the International Symposium on Phylogeny and Classification of Neotropical Fishes (Porto Alegre, Brazil, July 1997), de Pinna presented a talk about the interrelationships of Neotropical catfishes. He proposed a preliminary cladistic hypothesis that accepted 12 monophyletic groups of siluriforms. In at least three cases, the relationships between New World and Old World clades are well established: the South American diplomystids, the sister group to all other catfishes; the African mochokids, the sister group to the South American doradoid superfamily, which includes the doradids and the auchenipterids; and the South American aspredinids, the sister group to the Asian erethistids. Nevertheless, de Pinna's cladogram implies the existence of four more transcontinental phylogenetic relationships. The discovery of close inter-relationships between systematic groups otherwise isolated in a continental block is relevant, due to the fact that most groups of ostariophysean fishes, such as siluriforms, primarily inhabit freshwaters.

Catfish fossils include Andinichthys, Incaichthys, and Hoff-stetterichthys (family Andinichthyidae) from the Upper Cretaceous and early late Paleocene of Bolivia; Corydoras revelatus (family Callichthyidae) from the late Paleocene of Argentina; Hypsidoris farsonensis, the only known species of the family Hypsidoridae, from the early middle Eocene of Wyoming, United States; late Eocene or early Oligocene (about 37 million years ago) material from Antarctica; Hoplosternum sp. (family Callichthyidae) from the middle Miocene of Colombia; and some material of the arioid (from the Arioida group) material from coastal marine Eocene deposits from Camden (Arkansas, United States).

It has been shown, based on cladistic grounds, that the gymnotiforms, or electric knifefishes, are the group most closely related to the siluriforms. Some authors have chosen to include both orders under the Siluriformes, a lead not followed here.

Physical characteristics

Catfishes are well known and recognized worldwide by a few characteristics. They normally show one to four pairs of barbels on the head around the mouth: one nasal, one maxillary, and two on the lower jaw or mandible. The nasal and/or lower jaw barbels may be absent, but in any case, the maxillary barbels are the longest. As these threadlike structures have plenty of taste buds, they have chemosensory and tactile functions, allowing the small-eyed catfishes to gather food efficiently.

Catfishes usually have spiny rays at the front of the dorsal and pectoral fins. These thornlike structures are large, unsegmented, and strong elements, technically similar to the other lepidotrichia, the rays that support the fins. Most families of siluriforms have two dorsal fin spines; the first is tiny, but very important, because it locks the second, larger spine in an erect position. A catfish with erected, pointed spines is nicely protected from most potential predators. The spines in some families also deliver a toxin produced in an associated venom

gland. Although formidable weapons, spines are lacking in some catfish groups.

Most catfish species have a "naked" body because their leatherlike skin is completely scaleless. However, the so-called armored catfishes are covered at least partially by deeply embedded bony plates or by tubercles. Other external characteristics of catfishes are an adipose fin, usually present, sometimes rayed or preceded by a spine, and a small and toothless maxilla.

There are several internal characteristics worth mentioning, such as reductions, fusions, or absences in the set of skull bones typical of lower teleosts, as well as of intermuscular bones. The Weberian apparatus of catfishes involves five vertebrae, and their caudal skeleton is variable, ranging from six independent plates to the complete fusion of all its elements.

Distribution

Catfishes are mainly inhabitants of freshwaters, reaching their highest diversity in South America. There are more than 1,650 catfish species in South America distributed in eight monophyletic and endemic groups, including the richest family, the suckermouth armored catfishes (Loricariidae), with around 800 species. Loricariids and five other families form the armored catfishes, the largest monophyletic group of the order, with at least 1,150 species and a range between Costa Rica and Argentina. Included in this clade is the most speciose catfish genus, the plated catfishes Corydoras (Callichthyidae) with about 142 species. Other families of armored catfishes are the monotypic Nematogenyidae, the pencil or parasitic catfishes (Trichomycteridae), the spiny dwarf catfishes (Scoloplacidae), and the climbing, or South American hillstream, catfishes (Astroblepidae). The long-whiskered or antenna catfishes (Pimelodidae) used to be the second largest family, with about 300 species. However, since it is not a natural group, it was officially split in 2001 into three monophyletic families: the pimelodids (in the narrow sense), the heptapterids (Heptapteridae), and the pseudopimelodids (Pseudopimelodidae). In any case, Heptapteridae, the most species-rich group of the "old" long-whiskered catfishes with about 150 species, is widely distributed from Southern Mexico to Argentina. The remaining monophyletic groups of South American catfishes are the velvet or Patagonian catfishes (Diplomystidae), the whalelike catfishes (Cetopsidae), the doradoids (including the thorny or talking catfishes, Doradidae, and the driftwood catfishes, Auchenipteridae), and the banjo catfishes (Aspredinidae). The bullhead or North American freshwater catfishes (Ictaluridae), with 44 species, is officially the only family of the order endemic to North America, ranging as far south as Guatemala. The so-called Chiapas catfish was presented to the scientific community at the 2000 meeting of the American Society of Ichthyologists and Herpetologists; this unusual catfish seems to deserve its own family. So far, it is only known from southern Mexico.

Old World catfishes are also highly diverse; more than 1,000 species are known from Africa and Eurasia. The bagrid catfishes (Bagridae), the airbreathing or labyrinth catfishes (Clariidae), the glass catfishes (Schilbeidae), and the eeltail or tandan catfishes (Plotosidae) are the four families occurring in both Africa and Asia. Bagridae is the richest family of these widely distributed catfish clades, with about 130 species. The other three families include about 170 species. There are six catfish families endemic to Africa. Of them, the squeakers or upside-down catfishes (Mochokidae) is the richest, since it contains about 180 species; two-thirds of which are included in the genus Synodontis. The loach or African hillstream catfishes (Amphiliidae) has about 60 species. Other endemic African families are the claroteids (Claroteidae), the auchenoglanidids (Auchenoglanididae), the electric catfishes (Malapteruridae), and the austroglanidids (Austroglanididae); together these four groups contain more than 100 species.

Asia is next to South America in the number of endemic catfish families. However, these tend to be poorly speciated groups, usually with fewer than 30 species each. The sucker or Asian hillstream catfishes (Sisoridae) is the richest family, with a few more than 110 species. Other endemic Asian families are the stream or shortfin catfishes (Akysidae) with 27 species, the shark catfishes (Pangasiidae) with 26 species, the torrent or Asian loach catfishes (Amblycipitidae) with 25 species, the erethistids (Erethistidae) with 13 species, and the armorhead or Chinese catfishes (Claroglanididae) and the squarehead or frogmouth catfishes (Chacidae), both with 3 species. The sheatfishes (Siluridae) is the only family of catfishes extending its range to Europe; it includes about 100 species, only 2 of which occur in Europe.

Finally, two families have widely invaded the marine realm; interestingly, both groups include the only catfishes known from Australia. The eeltail catfishes, a rather small family of 27 species, is known from the Indian and the western Pacific Oceans and extends to Japan and Fiji. The sea catfishes (Ariidae) includes about 200 species in all the tropical continental shelves.

Habitat

Catfishes occupy practically all freshwater environments, where they are often the dominant group of fishes. Catfishes are mostly benthic and freshwater inhabitants, and they can be ubiquitous in the rivers of tropical continents such as South America and Asia, invading habitats such as riffles and waterfalls, as well as marginal, almost stagnant ponds. Some groups occupy the water column, swimming above the bottom. In those hovering catfishes some bizarre adaptations are noteworthy. Some sheatfishes and glass catfishes, for example, hover tail down, and both groups are schooling, transparent, with long barbels (one or four pairs), a long anal fin, a minute or absent adipose fin, a forked tail, and a dorsal fin completely lacking or represented by a sole reduced ray. Other catfishes, such as some banjo catfishes and most eeltail and sea catfishes, are estuarine and may venture even to deep-bottom continental-shelf environments or to offshore islands.

Behavior

Catfishes are generally bottom-dwelling, nocturnal, and solitary inhabitants of freshwater environments. However, an important minority are relatively specialized. For example, some sheatfishes, glass catfishes, and long-whiskered catfishes live far away from the bottom, are diurnally active, and may form schools. Eeltail catfishes and some thorny catfishes are well known for forming relatively large schools close to the bottom. Many South American species of armored catfishes are benthic and diurnal.

Feeding ecology and diet

Catfishes exhibit a wide array of feeding strategies. Most species live intimately linked to the bottom and feed mainly on invertebrates. Fish eaters are also abundant. For example, the squarehead, angler, and frogmouth catfishes (Chacidae) belong to a small group of Asian species that may use their maxillary barbels to attract smaller fishes to their enormous mouths. On the other hand, the Neotropical suckermouth armored catfishes (Loricariidae) are basically plant eaters, taking aquatic and terrestrial materials, such as algae and fallen leaves and trees. Catfishes, mainly those included in the pencil catfish family (Trichomycteridae), also engage in parasitic activities. Parasitic catfishes may be lepidophagous, targeting mucus, scales, and associated tissues (stegophyline trichomycterids), or hematophagous, swallowing blood (vandelliine trichomycterids). Some lepidophagous parasitic catfishes eat large pieces of flesh and enter the body cavities of their host. These species attack and devour commercially important catfishes trapped in nets or hooks and are therefore considered pests.

Catfishes are under the predatory pressure of almost all carnivores sharing their habitat. Even large predatory species are eaten as eggs, larvae, and juveniles. Their main fish predators are gars, bony tongues, trahiras, Nile perch, cichlids, and of course, other catfishes. Non-fish predators include crocodiles and caimans, and freshwater and coastal dolphins.

Reproductive biology

The usual process of catfish reproduction involves adult specimens with reduced or absent external sexual dimorphism and some courtship activity before the demersal spawning, followed by moderate engagement in parental care of the rather small eggs. Most guarding of eggs and fry is carried out by males. Nevertheless, females of some relatively large banjo catfish species, such as Aspredinichthys tibicen and Aspredo aspredo, manage to adhere the eggs after fertilization to spongy tentacles or cuplike depressions present seasonally on their bellies. It has been said that the mother nurtures the litter. Another highly derived system, brood parasitism, has been developed by a squeaker species, Synodontis multipunctatus, which could be referred to as an aquatic "cuckoo." This Lake Tanganyika mochokid shares its habitat with a mouth brooding species of Cichlidae. The catfish synchronizes its spawning activity to that of the cichlid, allowing the perciform female to ingest its eggs for mouth brooding. The process does not end when the squeaker eggs hatch. Since the squeaker eggs hatch before the cichlid eggs, the catfish fry feed upon the host's fry inside her mouth!

In many cases parental care by the male is highly significant. Perhaps the best example of this is the mouth-breeding sea catfish. Sea catfishes are relatively dimorphic: females develop pads or claspers on the pelvic fins and males shed the teeth on the roof of their mouth. The process by which the female transfers the fertilized eggs to the male's mouth is not clear. In any case, he fasts for as long as two months until the fry are released.

Conservation status

The IUCN Red List includes 66 siluriform species. One, the bagre graso (Rhizosomichthys totae), a pencil catfish from the Tota Lake, 9,845 ft (3,000 m) high in the Colombian Andes, is classified as Extinct. In addition, 8 species are listed as Critically Endangered; 7 as Endangered; 22 as Vulnerable; 4 as Lower Risk/Near Threatened; and 24 as Data Deficient.

Significance to humans

Catfishes are considered one of the more important orders of vertebrates, not only because more than one-tenth of living fishes are siluriforms, but because their relationship with humans covers many aspects of life and culture. Several hundred species are now used as food, and other species will be looked upon as a source of protein in the future. Some species are greatly appreciated as game and commercial fishes and reach high market prices, but some are simply the difference between starvation and survival for millions of humans. In addition, most catfishes can be used as aquarium fishes, a business that is not only worth millions of dollars, but gives urban populations the opportunity to get in touch with a significant part of nature.

Species accounts

List of Species

New Granada sea catfish

Ariopsis bonillai

family

Ariidae

taxonomy

Galeichthys bonillai Miles, 1945, Magdalena River, Honda, Colombia.

other common names

French: Mâchoiron requin; Spanish: Chivo cabezón, chivo cazón.

physical characteristics

Length 31.5 in (80 cm). Body naked, elongate, and robust; dorsal fin with one spine and seven soft rays; adipose fin present; pectoral fins with one spine and 10 soft rays; pelvic fins with six soft rays, inner rays strongly modified to form a hook in mature females; caudal fin deeply forked; head covered by a very rugose bony shield, well visible beneath the skin and extended anteriorly to opposite eyes, the posterior portion of the shield extends backward to meet the predorsal plate, which is large and crescent-shaped; three pairs of barbels; posterior pair of nostrils partly covered by a flap of skin; eye large, with free orbital rims. Dark gray to bluish gray dorsally, bluish white ventrally.

distribution

Southern Caribbean between Colombia and the Gulf of Venezuela.

habitat

Mainly inhabits coastal, brackish water, mangrove-lined lagoons, but has been collected in riverine environments as well as in shallow turbid marine waters.

behavior

Benthic over muddy bottoms; solitary or forms schools.

feeding ecology and diet

Omnivorous; feeds mainly on benthic invertebrates, including crustaceans and polychaetes, but also consumes insects, small fishes, algae, and detritus.

reproductive biology

As with all studied members of this family, engages in oral brooding; the male incubates the relatively large eggs in his mouth until hatching. Spawning occurs almost year round, with a peak in the Ciénaga Grande de Santa Marta between April and July. Fecundity is rather low, each female produces 24–39 eggs of about 0.5 in (1.3 cm). Sexual maturity is reached at sizes around 17 in (43 cm), but sexes can be told apart using external morphology at 7.5 in (19 cm). Males carry eggs and young for about two months.

conservation status

Classified as Endangered by the IUCN. This status is due to its endemicity to the southern Caribbean, combined with enormous pressure from artisan fisheries and significant habitat alteration. As a consequence of overfishing, the medium size of capture (12 in/30.5 cm) is well below the size of sexual maturity.

significance to humans

Fished for with hook and line, cast nets, and beach seines. Widely used as food by fishing communities and low-income populations of cities and towns in the Colombian Caribbean. By 2002 attempts to develop a specific aquaculture procedure were being made. Young may be used also as an aquarium species.

Guitarrita

Dysichthys coracoideus

family

Aspredinidae

taxonomy

Dysichthys coracoideus Cope, 1874, Nauta, Peru. Nomenclatural situation is confused due to lack of clarity of the type species of genus Bunocephalus. Sometimes divided in two subspecies: D. coracoideus coracoideus for the Amazonas, and D. coracoideus amaurus for the Guyanas; the last subspecies may be treated as a separate species (D. amaurus) under the common name camouflaged catfish.

other common names

English: Guitarrero, little guitar; French: Poisson banjo; Spanish: Catalina, guitarrita; Portuguese: Rabeca; Guyanas indigenous languages: Grongron, kronkron.

physical characteristics

Length 4.3 in (11.0 cm). Body naked but covered by papillae or bumps; dorsal fin spineless, with five rays; adipose fin absent; anal fin short, with seven rays; pectoral fins with a strong serrated spine; caudal peduncle long and slender; caudal fin rounded; head and anterior part of body depressed; head covered by thickened bones; mouth small and anterior; three pairs of relatively short barbels; eyes small and on top of head; gill opening a short slit; anterior and posterior borders of pectoral fin spines with strong and recurved teeth.

distribution

South America in the Amazon River basin and Guyanas.

habitat

Fresh waters in ponds and small forest streams rich in plant remains.

behavior

Bottom dwelling; swims by wavelike motion of body and tail; ejection of water through the gill slits results in a jerky forward movement.

feeding ecology and diet

Omnivorous, even feeds on organic matter from the bottom.

reproductive biology

Spawns in groups; female does not carry her eggs, but lays 4,000–5,000 eggs each time on sandy bottom nests made by the male, which guards the eggs and fry.

conservation status

Not listed by the IUCN.

significance to humans

Too small to be of interest as a food fish. However, it is an important aquarium fish which has been spawned in captivity.

Dwarf corydoras

Corydoras hastatus

family

Callichthyidae

taxonomy

Corydoras hastatus Eigenmann and Eigenmann, 1888, Villa Bella (=Parintins), Amazonas, Brazil.

other common names

English: Pygmy corydoras; French: Corydoras nain; Spanish: Coridoras enano, corredora.

physical characteristics

Length 1.4 in (3.5 cm). Body compressed, with two rows of overlapping bony plates on each side, the nuchal scutes not meeting dorsally; dorsal fin with a strong spine and seven soft rays; spine at anterior border of adipose fin; pectoral fins with a strong spine and eight rays; caudal fin forked; head compressed; mouth small and ventral; two pairs of well-developed barbels.

distribution

South America in Amazon and Paraguay River basins.

habitat

Fresh waters in ponds.

behavior

Forms small schools in midwater among aquatic vegetation. It rests on any kind of plant leaves in normal position or with the ventral surface up against the bottom of a leaf, high above the bottom. Normally swims by rapidly moving the pectoral fins, which, combined with a rapid breathing rate, gives it a rather nervous appearance.

feeding ecology and diet

Feeds among plants, as well as from the bottom, on small invertebrates and on detritus.

reproductive biology

Sexually dimorphic; males are more elongate and their dorsal fins are more pointed. Near the time of spawning, both sexes clean their surroundings, mainly plant leaves. Courtship consists first of dashing about back and forth and up and down. Then the so-called "T" position is assumed close to the bottom; the female positions herself at the side of the male, close to his vent, pushing him with her head while constantly moving her barbels. After some "trembling" by both sexes, the female lays an egg. After fertilization the egg is carried in the female's ventral pouch and deposited over one of the leaves cleaned before. The female continues to spawn single eggs for one to two hours over three or four consecutive days. At this rate, a total of 30–60 eggs are spawned by each female. Since group spawning is normal, 300 eggs or more are frequently deposited. Fry 0.20 in (0.5 cm) long hatch usually after three to four days, and mature in about 200 days. The parents can spawn again after two weeks.

conservation status

Not listed by the IUCN.

significance to humans

Commercially important for the aquarium trade.

Squarehead catfish

Chaca chaca

family

Chacidae

taxonomy

Platystacus chaca Hamilton, 1822, northeastern Bengal.

other common names

English: Angler catfish, chaca, chega, Indian frog-mouth catfish; Spanish: Bagre cabezicuadrado.

physical characteristics

Length 9.1 in (23 cm). Body compressed posteriorly; with many fine granulations; dorsal fin with a short spine and four soft rays; adipose fin a low ridge confluent with caudal fin; pectoral fin with one serrated spine and five soft rays; pelvic fins large, with six rays; a row of cirri above the lateral line; head broad and depressed, almost square, with a deep longitudinal groove located dorsally; mouth terminal, very wide, provided with appendages resembling barbels; three pairs of small barbels; eyes very small.

distribution

Asia in India, Bangladesh, and Nepal.

habitat

Freshwater; bottom dweller in rivers, canals, ponds, and flood plains.

behavior

Prefers soft bottoms, where it hides lying still on the river bed. Depends completely on this concealment for protection, remaining motionless even after being touched.

feeding ecology and diet

Sometimes moves its tiny maxillary barbels in a jerky motion to lure small fishes, including gouramies and cyprinids, near its large mouth; may take fishes as large as one-half its length.

reproductive biology

Nothing known.

conservation status

Not listed by the IUCN.

significance to humans

Commonly fished but not eaten probably due to its odd appearance. Sometimes used as an aquarium fish. The dorsal spine can inflict painful wounds if the fish is stepped on.

Sharptooth catfish

Clarias gariepinus

family

Clariidae

taxonomy

Silurus (Heterobranchus) gariepinus Burchell, 1822, Smidtsdrift, Vaal River, Cape Province, South Africa.

other common names

English: Mubondo, North African catfish, Zambezi barbel; Spanish: Bagre dientón.

physical characteristics

Length 5.6 ft (1.7 m); weight 132 lb (60 kg). Body naked and elongate; dorsal fin base very long, with 61–80 rays, not preceded by a spine, not continuous with caudal fin; adipose fin absent; pectoral fin spine serrated only on its external border; anal fin long, separated from caudal fin; caudal fin rounded; head depressed, covered with rugose bony plates; mouth terminal and transverse; four pairs of barbels; eyes superior, relatively small, and with a free orbital rim; gill openings wide; air-breathing labyrinthic organ arising from second, third, and fourth gill arches. Coloration countershaded, dark gray dorsally, milky white ventrally, ventral surface of head in adults with a black longitudinal band in each side; band absent in juveniles.

distribution

Africa in Niger and Nile River basins; also the Limpopo, Orange-Vaal, Okavango, and Cunene Rivers, South Africa, and in the Middle East, including Israel, Jordan, Lebanon, and Syria.

habitat

Benthopelagic in fresh waters and upper estuaries 13–262 ft (4–80 m) deep, but more common in shallow environments.

behavior

Widely resistant to challenging environmental conditions; the accessory labyrinthic organ allows clariid catfishes to breathe air under dry conditions. Favors shallow marginal areas, but may appear in the open; nocturnal. Capable of walking through dry land using tough pectoral fin spines. May also discharge electricity during intraspecific agonistic behavior.

feeding ecology and diet

Omnivorous bottom feeder, feeds on insects, fishes, crustaceans, mollusks, plankton, fruits, plants, small birds, and carrion. Occasionally feeds at the surface.

reproductive biology

Migrates upstream or to lakeshores in large numbers to spawn immediately after the first heavy showers of the rainy season. Sexually dimorphic, both males and females have elongated sexual organs, but male organ has cone-shaped tip. Spawning is nocturnal in shallow waters; eggs, which have an adhesive disk and are less than 0.10 in (0.25 cm) long, are not protected. Eggs hatch in one or two days. Juveniles stay in shallow, protected waters for about six months, migrating downstream before their nursery area dries up.

conservation status

Not listed by the IUCN.

significance to humans

Although of relatively minor importance for fisheries, this is a valuable aquaculture species, due to its hardiness, rapid growth, ease of feeding and handling, and flesh quality. Also considered a game fish. Widely introduced to almost all Africa, and to some European, Asian, and South American countries; negative ecological impact has been reported. Trade restricted in Germany.

Blue-eye catfish

Amblydoras hancockii

family

Doradidae

taxonomy

Doras hancockii Valenciennes, 1840, Demerara, Guyana.

other common names

English: False talking catfish, Hancock's amblydoras, purring catfish; Spanish: Bagre ojiazul; Portuguese: Quiri-quiri.

physical characteristics

Length 5.9 in (15 cm). Body somewhat elongated, with a row of 24–28 lateral bony plates, each provided with a posteriorly directed hook; anterior granulations of body confluent into a large buckler; dorsal fin spine grooved, but lacking teeth, six dorsal soft rays; interdorsal plate absent; adipose fin present; pectoral fins' spines serrated on both edges, capable, as the dorsal spine, of being erected and locked; caudal fin truncated; head large and depressed; mouth terminal; three pairs of unbranched barbels; eye located in the middle of head. Dark brown to violet dorsally, white ventrally, a white strip along the body; eyes bright blue.

distribution

South America in Guyana and eastern Brazil to Peru and Bolivia.

habitat

Freshwater in coastal swamps, flood plains, ponds, and creeks.

behavior

Lives in schools, sometimes by hundreds, hiding during the day in places with the bottom covered by plant material, mainly fallen trees and leaves. Resists desiccation by crawling to a suitable body of water. Can produce sounds by different combinations of pectoral spines, swim bladder, and the sophisticated internal elastic spring apparatus.

feeding ecology and diet

Nocturnal plant and detritus eater in the wild, but reported to eat animal material, such as worms, in captivity.

reproductive biology

Spawns in the rainy season. The male builds a nest of bubbles, leaves, and other plant material at the surface, where the female lays the eggs in a flattened cluster. The male guards the nest until egg hatching.

conservation status

Not listed by the IUCN.

significance to humans

Not important to fisheries due to its small size. Commercially important as an aquarium fish.

Channel catfish

Ictalurus punctatus

family

Ictaluridae

taxonomy

Silurus punctatus Rafinesque, 1818, Ohio River, United States.

other common names

English: Blue channel catfish, eel catfish, fiddler, forked-tail cat, government cat, Mississippi cat, river cat, sand cat, sharpie, silver cat, speckled cat, spot, white cat, willow cat; Spanish: Bagre de canal.

physical characteristics

Length 4.3 ft (1.32 m); weight 58 lb (26.3 kg). Body naked and elongate; dorsal fin with a spine and six or seven soft rays; adipose fin small, remote from caudal fin, which is deeply forked; pectoral fins with a spine with large posterior serrae; pelvic fins with eight soft rays; mouth subterminal to inferior; four pairs of barbels; eye large and oval. Young mottled, brownish above, whitish below; adults mainly deep slate brown.

distribution

North America, native to central drainages of the United States and Mexico into southern Canada east of the Rocky Mountains, and possibly parts of the Atlantic coast. Original distribution somewhat unclear due to extensive introductions to the Atlantic coast and elsewhere. Fossils 10–20 million years old have been reported.

habitat

Freshwater in clear, well-oxygenated streams, and medium to large rivers with swift currents over relatively hard bottoms, including sand, gravel, and rocks. Also in quiet waters of lakes, reservoirs, and ponds. May enter brackish waters. Taken as deep as 49 ft (15 m).

behavior

Benthic. Capable of relatively long migrations. Travels upstream in the spring and downstream in the fall. Young school close to the bottom at light hours during their first year, scattering at night.

feeding ecology and diet

A nocturnal carnivore, feeds mainly on small fishes, crustaceans, insects, and mollusks. Reported to also eat filamentous green algae. Well known for taking almost any bait, including rotten items.

reproductive biology

Spawning occurs during the day in nests guarded by the male, beginning early spring in the south but later in the northern parts of its range, usually when the water warms to 60–75°F (16–24°C). Eggs hatch in 6–10 days. Maturity is reached in 2–5 years at about 1 ft (0.3 m) long. Reported to live 16 years.

conservation status

Not threatened.

significance to humans

Highly important fishery, aquaculture, aquarium, and game species. It is a top sport fish, and is actively farmed. Used in "pay as you fish" ponds. Mississippi produces over 90% of the channel catfish farm-raised in the United States. In 1996, Mississippi ponds produced 334 million lb (about 152 million kg) valued at $265 million. Trade is restricted in Germany, where it is considered a potential pest.

Branched bristlenose catfish

Ancistrus triradiatus

family

Loricariidae

taxonomy

Ancistrus triradiatus Eigenmann, 1918, Quebrada Gramalote, Barrigona, Villavicencio, Departamento del Meta, Colombia.

other common names

Spanish: Cucha barbuda.

physical characteristics

Length 4.7 in (12 cm). Body broad and depressed, covered with bony plates, 23–26 in the lower lateral series; belly naked; dorsal fin with one spine and eight rays; adipose fin present, not attached to adipose fin by a membrane; caudal fin truncate; anal fin with one spine and three to four rays; pectoral fin spine short, not reaching the origin of pelvic fin; anterior portion of upper snout surface naked and with well-developed branching barbels in males, barbels small and simple in females; mouth ventral; teeth small, numerous, and bifid; opercular bones armed with about a dozen spines.

distribution

South America in middle and lower Orinoco River tributaries; Venezuelan and Colombian Caribbean coastal drainages, including the Magdalena River; Lake Maracaibo Basin, including the Catatumbo River.

habitat

Fresh waters. Benthic, in fast-running mountain streams with coarse pebble bottoms; lives as high up as 3,300 ft (1,000 m).

behavior

Relatively shy fishes, usually live in caves or below rocks.

feeding ecology and diet

Omnivorous, feeds on filamentous algae and microorganisms growing on rocks, logs, and leaves. Also rasps rotten wood and ingests the cellulose. The lignin is reportedly important for their digestive processes.

reproductive biology

The male selects an area such as under a log or a rocky cave and after some hours of courtship the female lays 50–150 yellowish to orange eggs, about 0.10 in (2.5 mm) long, which are guarded by the male and hatch in one week or less.

conservation status

Not listed by the IUCN.

significance to humans

Unimportant for fisheries. Used as an aquarium fish, it has been spawned in captivity.

Electric catfish

Malapterurus electricus

family

Malapteruridae

taxonomy

Silurus electricus Gmelin, 1789, Rosetta, Nile River.

other common names

French: Silure éléctrique; Spanish: Bagre eléctrico.

physical characteristics

Length 4 ft (1.22 m); weight 59.5 lb (27 kg). Body naked and sausage-shaped; a thick subdermal electrogenic organ derived from pectoral musculature extends the entire length and circumference of the fish; dorsal fin absent; adipose and anal fins far back; pectoral fin spine absent; swim bladder with an elongate posterior chamber; caudal fin rounded; mouth terminal; three pairs of long and fleshy barbels; eyes small and without a free border. Very large spots on the body and vertical bars on posterior part of the body and caudal fin.

distribution

Africa in Nile, Chad, and Niger basins.

habitat

Benthic in freshwater.

behavior

Rests around rocks and roots in quiet waters during the day, becoming active at night. Intermittently produces electric discharges of basically two types: high frequency, used for self-defense and prey capture, and low frequency, associated with prey detection. Discharges can be 100–400 V, depending on catfish size. Generally, the initial shock, short and sharp, is followed by less intense secondary discharges.

feeding ecology and diet

A poor swimmer, feeds mainly on aquatic invertebrates and small fishes stunned by its electric discharges. Food items reported from stomachs are shrimps and fishes, such as cichlids, clupeids, schilbeids, bagrids, cyprinids, and characids.

reproductive biology

Forms pairs during the rainy season; spawning occurs in excavated holes. Reported to live 10 years.

conservation status

Not listed by the IUCN.

significance to humans

Used in subsistence fisheries and considered a game fish; also important for show aquariums. However, it is better known for its strong electric discharges, which are supposed to be capable of knocking down a person if the catfish is stepped on. Humans have known about these electric capabilities for over 5,000 years.

Blotched upsidedown catfish

Synodontis nigriventris

family

Mochokidae

taxonomy

Synodontis nigriventris David, 1936, Buta, Congo Democratic Republic (=Zaire).

other common names

Spanish: Bagre manchado al revés.

physical characteristics

Length 3.8 in (9.6 cm). Body naked and relatively elongated; dorsal and pectoral fin spines strong and with a locking mechanism; adipose fin very large, not rayed; caudal fin forked; head bony, with a nape shield; mouth relatively small, lips not suckerlike; three pairs of barbels, mandibular barbels branched, eye with a free border. Color reverse countershaded, dorsal surface light, ventral surface dark.

distribution

Africa in Central Congo basin.

habitat

Benthopelagic in fresh water.

behavior

Schools by the thousands. Large fishes swim upside down and may be able to escape predation by hiding with the ventral surface up under a log. Young swim in a conventional way. The pectoral fin spine produces a squeaking sound when it moves in its socket.

feeding ecology and diet

Nocturnal. Uses its inverted swimming position to feed on filamentous algae that grow on cave ceilings and on the under-sides of leaves and other aquatic vegetation, and also to take terrestrial insects and other material from the water surface. Also feeds on bottom material, such as plant and fish remains, crustaceans, and insect larvae.

reproductive biology

Females lay about 100 eggs under a rock or on the roof of a cave; eggs hatch in about seven days.

conservation status

Not listed by the IUCN.

significance to humans

Unimportant for fisheries because of its small size. A widely used aquarium fish, has been spawned in captivity.

Iridescent shark-catfish

Pangasius hypophthalmus

family

Pangasiidae

taxonomy

Helicophagus hypophthalmus Sauvage, 1878, Laos.

other common names

English: Candy-striped catfish, sutchi catfish, sharkfin catfish, silver catfish, swai; Spanish: Bagre sutchi.

physical characteristics

Length 4.3 ft (1.3 m); weight 34 lb (15.5 kg). Body naked, compressed; predorsal area relatively keeled; dorsal fin far forward, with a sharp serrated spine and six soft rays; adipose fin small; anal fin long, with about 30–40 rays; pectoral fins with a sharp spine; caudal fin forked; head covered by soft skin; mouth small, subterminal; two pairs of barbels (maxillary and mandibular) that shorten with age; eyes above and below the corner of the mouth with a free orbital rim. Young with two black stripes, one along the lateral line and another below it; adults mainly gray.

distribution

Southeast Asia (Indochina) in Mekong and Chao Phraya basins. Introduced into streams for aquaculture.

habitat

Freshwater in large rivers.

behavior

Benthic. Undergoes long upstream migrations, both reproductive and trophic, in late fall and early winter, migrates downstream in late spring and summer. Reported to be always on the move when in confinement; capable of sound production.

feeding ecology and diet

Omnivorous, feeds on fishes, crustaceans, mollusks, and plant litter. Young tend to be carnivorous, eating more plants while growing.

reproductive biology

Since eggs appear from March to August, it is believed that the downstream migration is not only trophic, but also reproductive.

conservation status

Not listed by the IUCN.

significance to humans

Important commercially for fisheries, aquaculture, and the aquarium trade.

Lau-lau

Brachyplatystoma filamentosum

family

Pimelodidae

taxonomy

Pimelodus filamentosus Lichtenstein, 1819, Brazil.

other common names

French: Torch; Spanish: Lechero, plumita, valentón, zungaro saltón; Portuguese: Filhote, piraíba, piratinga; Guyanas indigenous languages: Axakwan, lektaima, pilau.

physical characteristics

Length 11.8 ft (3.6 m); weight 440 lb (200 kg). Body naked; dorsal and pectoral fins with one spine; adipose fin long based; caudal fin deeply forked, upper and lower fin rays very long; head broad; snout very depressed; mouth slightly ventral; maxillary barbels very long, one to two times the length of the body in juveniles, two-thirds the length of the body in adults; eyes small, dorsolaterally located, with a free orbital rim. Color dark gray dorsally, whitish ventrally.

distribution

South America in Amazon and Orinoco basins, also main rivers of the Guyanas and northeastern Brazil.

habitat

Channels of large rivers, including muddy, black-water and clear-water tributaries, and upper reaches of estuaries. Young specimens occur in flood plains and ponds as well as on the main river channels and even in brackish water.

behavior

Soft-bottom dweller, but a good swimmer capable of long migrations.

feeding ecology and diet

Piscivorous, mainly consuming characids, catfishes, and knifefishes it swallows whole. Monkeys have also been reported from the stomachs of large specimens.

reproductive biology

Medium sizes at maturity in the lower Caquetá (=Japurá) river are 59 in (1.5 m) standard length for females, 51 in (1.3 m) for males. Estimations of fecundity are variable, figures range from 60,000 eggs for a 143 lb (65 kg) specimen to one million eggs for a 106 lb (48 kg) female. Spawning in Venezuela coincides with the rainy season; young specimens are found in July and August.

conservation status

Not listed by the IUCN. However, it is considered endangered in Colombia due to overfishing, and most specimens fished at the turn of the twentieth century in that South American country were immature. Minimum legal capture size in Colombia is 40 in (1 m).

significance to humans

Highly important commercial fish captured using nets and longlines, flesh is considered of excellent quality. Also a valuable game fish. Older literature reports that lau-lau occasionally prey on humans.

Redtail catfish

Phractocephalus hemioliopterus

family

Pimelodidae

taxonomy

Silurus hemioliopterus Bloch and Schneider, 1801, Maranham River, Brazil.

other common names

Spanish: Bagre colirrojo, guacamayo, pez torre; Portuguese: Bigorilo, guacamayo, peixe-arara, pirarara.

physical characteristics

Length 4.4 ft (1.34 m); weight at least to 176.2 lb (80 kg). Body stout and naked; dorsal fin with one spine and seven rays; adipose fin short and high; caudal fin broad and almost square; head as broad as high, flattened dorsally; maxillary barbels extending at least to dorsal fin level; eyes small, with free margins; nostrils widely separated; pectoral fins spine thick with sharp, recurved teeth posteriorly. Coloration countershaded, vertical fins with bright orange tips, white ventrally.

distribution

South America in Amazon and Orinoco River basins. Reported from Venezuelan fossils six million years old.

habitat

Freshwater.

behavior

Bottom dwelling. In the upper Caquetá River (Colombia) its upstream migration occurs between March and June.

feeding ecology and diet

Omnivorous, feeds on animals (fishes and crabs) and plant material (fruits).

reproductive biology

Nothing known.

conservation status

Not listed by the IUCN.

significance to humans

Important for subsistence fisheries, also a game fish. Commercially important as an aquarium fish; introduced, but not established, in Florida.

Tiger shovelnose catfish

Pseudoplatystoma fasciatum

family

Pimelodidae

taxonomy

Silurus fasciatus Linnaeus, 1766, Brazil, Suriname. The population restricted to the Magdalena-Cauca basin (Colombia), usually included under this name, seems to deserve status as a species.

other common names

English: Tiger catfish, bared sorubim, tumare; French (Creole): Poson-tig, torch-tig; Spanish: Bagre pintadillo, bagre rayado, bagre tigre, zungaro doncella; Portuguese: Pintado, surubim, surubim-lenha.

physical characteristics

Length 3.4 ft (1.05 m); weight 154.2 lb (70 kg). Body naked; dorsal and pectoral fin spines well developed and covered by thick skin; well-developed adipose fin; caudal fin forked; head large and depressed; upper jaw overhanging the lower jaw; maxillary barbels relatively short, not extending to anal fin; eyes relatively small and dorsally located; dorsal skull fontanel relatively short and shallow. Coloration dark gray dorsally, whitish ventrally, crossed by dark bands or loops.

distribution

South America in Amazon, Corintijns, Essequibo, Orinoco, and Paraná River basins.

habitat

Fresh waters in lakes, flooded plains, and forests, main river channels, and floating meadows. Absent from estuaries. Occurs at maximum depth of 16 ft (4.9 m).

behavior

Bottom dweller. Strongly migratory. In the Amazon basin, undergoes two annual migrations: a feeding one in the dry season and another at the beginning of the rainy season. In Venezuela, follows the migratory pattern of the bocachicos (Prochilodontidae) and other nomadic fishes.

feeding ecology and diet

Basically a nocturnal fish eater, consumes mainly characiform fishes, as well as other catfishes and cichlids, which it swallows whole. In the Apure River (Venezuela), 34 species of migratory fishes have been found in stomach contents. Spiders, crabs, and seeds are also taken.

reproductive biology

Reproductive season in the Orinoco basin runs between March and June. Median sizes of gonad maturity in eastern Colombia estimated at 32.7 in (83 cm) standard length for females, and 23.6–41.3 in (60–105 cm) for males; relative fecundity was estimated as well as about 30,000 eggs per pound (about 60,000 per kg). Sizes at first sexual maturation reported as 22 in (56 cm) for females and 17.7 in (45 cm) for males.

conservation status

Not listed by the IUCN. However, it is considered threatened in Colombia. The population from the Magdalena-Cauca basin is considered critically endangered. That country has tried to regulate the exploitation of the barred sorubim, as well as that of the northern Colombian population, establishing minimum sizes of capture and fishing seasons.

significance to humans

Enormously important for commercial fisheries in most countries where it occurs because of its excellent tasting yellowish flesh. Cultured in Colombia and Venezuela. Also a game fish and traded for show aquariums.

Coral catfish

Plotosus lineatus

family

Plotosidae

taxonomy

Silurus lineatus Thunberg, 1787, Indian Ocean.

other common names

English: Bumblebee catfish, striped eel-catfish; Spanish: Bagreanguila rayado; Afrikaans: Streep-baberpaling.

physical characteristics

Length 12.6 in (32 cm). Body naked, eel-like; dorsal fin short, with a sharp, highly venomous, spine armed with relatively small teeth on both borders, and four rays; no adipose fin; pectoral fins spines serrated and highly venomous; tail pointed, caudodorsal fin rays extending forward ahead of midbody, lower caudal rays joining the long anal fin, forming a continuous fin with 139–200 rays; lateral line fully developed; dendritic organs present behind vent; mouth transverse; four pairs of relatively short barbels; eye relatively small with free orbital margins. Young black with two or three white or yellow stripes, adults mainly gray brown.

distribution

Indian and western Pacific Oceans, from the Red Sea and East Africa, including Madagascar, to Samoa, southern Japan and Korea, Australia, Lord Howe, Palau and Yap Islands.

habitat

Marine. The only catfish observed in coral reefs, also in tide pools, brackish environments, and freshwater; bottom dweller to about 200 ft (61 m) deep.

behavior

Solitary or forms tight shoals of hundreds in shallow water and tide pools, sometimes covering the bottom; schools may break into smaller pods that move coordinately. Schooling confuses and discourages predators.

feeding ecology and diet

Eats mainly invertebrates, such as crustaceans, mollusks, and worms, and fishes taken from the soft bottoms.

reproductive biology

Oviparous; the eggs are spherical, a little larger than 0.10 in (0.25 cm), nonadhesive, demersal; larvae are planktonic. In Japan reproduction occurs in early summer, the male builds and guards a nest with debris and rocks where the female deposits her eggs; the eggs hatch in 10 days or less. Females reach maturity in about one year, at a length of 5.5 in (14 cm). Maximum reported age is seven years.

conservation status

Not listed by the IUCN.

significance to humans

The venomous fin spines are very dangerous (but rarely fatal); therefore all users of coastal waters, including bathers, swimmers, divers, and fishermen should be very cautious. Pectoral fin spines receive venom from the axillary and pectoral spine glands. Nevertheless, these fishes are used as food, mainly in Africa, and as aquarium fishes; in Japan they are kept and spawned in public and private aquaria.

Glass catfish

Kryptopterus bicirrhis

family

Siluridae

taxonomy

Silurus bicirrhis Valenciennes, 1840, Java, Indonesia.

other common names

English: Phantom glass catfish; Spanish: Bagre vítreo.

physical characteristics

Length 5.9 in (15 cm). Body naked, strongly compressed; dorsal profile arched with a nuchal concavity; dorsal fin rudimentary, represented by only one short ray; adipose fin absent; anal fin base very elongate, with 55–68 rays; pectoral fins longer than head; pelvic fins small; caudal fin forked; mouth very small, oblique; one pair of barbels on lower jaw, maxillary barbels elongate, reaching to the anal fin; eye large, subcutaneous. Body translucent, internal features such as blood vessels and backbone visible, gut covered by a silvery peritoneum; depending on light the body may reflect iridescent colors, ranging from yellow to violet, or even fluorescent blue in twilight.

distribution

Asia in Mekong, Chao Phraya and Xe Bangfai basins, Malay Peninsula, Java, Sumatra, and Borneo.

habitat

Freshwater. Benthopelagic in large rivers and flooded plains, favors turbid shady waters.

behavior

Free-swimming, shoaling species. In captivity, the group stays in a dark corner during light hours, only disturbed by individuals changing places.

feeding ecology and diet

A diurnal carnivore, feeds on pelagic and planktonic invertebrates, such as hemipterans, other insects, worms, and crustaceans, and small fishes. In captivity only takes floating items, it never disturbs the bottom looking for food.

reproductive biology

Has not been spawned in captivity. No information from the wild.

conservation status

Not listed by the IUCN.

significance to humans

An important aquarium species. Also used to make the fish sauce prahoc.

European wels

Silurus glanis

family

Siluridae

taxonomy

Silurus glanis Linnaeus, 1758, Orient, European lakes.

other common names

English: Catfish, Danube catfish, European catfish, sheatfish; German: Wels; French: Silure glane; Spanish: Bagre europeo.

physical characteristics

Length 16.5 ft (5 m); weight 726 lb (330 kg). Body naked, robust, anteriorly compressed; dorsal fin with 1 spine and 4–5 rays; adipose fin absent; anal fin base very elongate, with 90–95 rays covered by integument for most of their length; pectoral fin spine stout; pectoral and pelvic fins short; caudal fin rounded; head broad and depressed; mouth terminal; maxillary barbels heavy, flattened.

distribution

Eurasia, including Baltic, Black, and Aral Seas estuaries.

habitat

Fresh and brackish waters, including quiet, shallow places such as marshes, lagoons, backwaters, and large lakes, and as deep as 98 ft (30 m) in large rivers and dams.

behavior

Benthic, occurring mainly over mud and sandy bottoms, where it hides in holes and under logs or tree roots during day hours; active during the night. Considered nonmigratory; however, in the Baltic Sea it reportedly undergoes short spawning migrations upriver, returning to spend winter months in deeper waters close to the river mouth.

feeding ecology and diet

Nocturnal and highly carnivorous, feeds on almost any aquatic animal. Juveniles consume bottom-living invertebrates; adults ingest large crustaceans, fishes, amphibians, ducks and other birds, as well as water voles and other small mammals.

reproductive biology

Spawning takes place in shallow lakes and on flooded areas during warm seasons, and even in saltwater in the Aral Sea. No nest building activity, but males do protect the adhesive eggs, 0.10 in (0.25 cm) each, which stick to aquatic vegetation or to large pieces of detritus, sometimes in numbers over 100,000. Hatching occurs in about 20 days. Reported to live 30 years.

conservation status

Not listed by the IUCN; however, it appears in Appendix III of the Bern Convention (protected fauna). Considered a potential pest that produces a negative ecological impact when introduced, but it does not always become well established after transplantation.

significance to humans

Important commercial and sport fish throughout its range. Marketed fresh, canned, and frozen. An industry based on this species in eastern Europe and in countries of the former Soviet Union produces leather from the skin, glue from the gas bladder and bones, and cheap caviar from the eggs.

Candiru

Vandellia cirrhosa

family

Trichomycteridae

taxonomy

Vandellia cirrhosa Valenciennes, 1846, probably South America.

other common names

Spanish: Candirú.

physical characteristics

Length 1 in (2.5 cm). Body naked and very elongate; dorsal fin short, without a pungent spine, its origin posterior to pelvic fins; adipose fin absent; anal fin origin behind dorsal fin base, short; mouth narrow and suckerlike, inferiorly located; lower jaw toothless; mental barbels absent; eyes without free margins; opercular bones with spines. With a yellowish tinge or almost transparent.

distribution

South America in the Amazon River basin.

habitat

Freshwaters. Benthic, burrows in sandy bottoms.

behavior

Parasitic, enters the gill cavity of larger fishes, frequently long-whiskered catfishes, to suck blood.

feeding ecology and diet

An obligate parasite that in captivity refuses any kind of food. However, it attacks a living fish by entering the gill chamber when inhaled water is expelled. Once in place, the candiru lodges itself using its opercular spines, bites off tips of host's gill filaments, and gorges with flowing blood. The candiru's body can distend considerably, and after few minutes of feeding it drops off to the bottom, where it burrows or just remains quiet.

reproductive biology

Nothing known.

conservation status

Not listed by the IUCN.

significance to humans

Known to enter the urogenital openings of bathers, usually if they happen to urinate under water. The candiru swims up the flow of urine, possibly mistaking it for the water flow from a gill cavity. After penetrating as far as possible, the fish locks its opercular spines into position. This has obviously serious consequences for both the fish and the person, since the candiru can only be removed by surgery. Humans in its range protect themselves by wearing tight clothing when swimming (and by refraining from urinating underwater).

Resources

Books

Barthem, Ronaldo, and Michael Goulding. The Catfish Connection. New York: Columbia University Press, 1997.

Berra, Tim M. Freshwater Fish Distribution. San Diego: Academic Press, 2001.

Burgess, Warren E. An Atlas of Freshwater and Marine Catfishes. Neptune City, NJ: T.F.H, 1989.

Ferraris, Carl J., Jr. "Catfishes and Knifefishes." In Encyclopedia of Fishes, edited by John R. Paxton and William N. Eschmeyer. San Diego: Academic Press, 1995.

Galvis, Germán, José Iván Mojica, and Mauricio Camargo. Peces del Catatumbo. Bogotá: Asociación Cravo Norte, 1997.

Helfman, Gene S., Bruce B. Collette, and Douglas E. Facey. The Diversity of Fishes. Malden, MS: Blackwell Science, 1997.

Mejía, Luz Stella, and Arturo Acero P., eds. Libro Rojo de Peces Marinos de Colombia. Bogotá: Invemar, Instituto de Ciencias Naturales, Ministerio del Medio Ambiente, 2002.

Mojica, José Iván, Claudia Castellanos, José Saulo Usma, and Ricardo Álvarez, eds. Libro Rojo de Peces Dulceacuícolas de Colombia. Bogotá: Instituto de Ciencias Naturales, Ministerio del Medio Ambiente, 2002.

Nelson, Joseph S. Fishes of the World. New York: John Wiley & Sons, 1994.

De Pinna, Mario C. C. "Phylogenetic Relationships of Neotropical Siluriformes (Teleostei: Ostariophysi): Historical Overview and Synthesis of Hypotheses." In Phylogeny and Classification of Neotropical Fishes, edited by L. Malabarba, R. Reis, R. Vari, Z. Lucena, and C. Lucena. Porto Alegre, Brazil: Edipucrs, 1998.

Ross, Stephen T. Inland Fishes of Mississippi. Jackson: University Press of Mississippi, 2001.

Other

"All Catfish Species Inventory" [cited February 7, 2003]. <http://clade.acnatsci.org/allcatfish>

"Fishbase" [cited February 7, 2003]. <http://www.fishbase.org>

"Planet Catfish" [cited February 7, 2003]. <http://www.planetcatfish.com>

"ScotCat" [cited February 7, 2003]. <http://www.scotcat.com>

Arturo Acero, MSc