Labroidei I

(Cichlids and surfperches)

Class Actinopterygii

Order Perciformes

Suborder Labroidei

Number of families 2

Evolution and systematics

The families Cichlidae (cichlids) and Embiotocidae (surfperches) have traditionally been grouped in the suborder Labroidei, along with Labridae (wrasses), Scaridae (parrotfishes), Pomacentridae (damselfishes), and Odacidae (western Pacific butterfishes). These groups were first suggested to share a common ancestry by Müller in 1843. All possess a pharyngeal jaw apparatus (a second set of jaws in the throat) that aids in the processing of food, and the morphological characters supporting their close relationship are all a part of this functional complex. Characters used to unite labroids include fused fifth ceratobranchials that bear teeth, a muscle sling suspending the lower pharyngeal jaw from the skull, an articulation between the upper pharyngeal jaws and the base of the skull without intervening muscle, and an undivided sheet of sphincter esophagi muscle. The reliability of these characters has been questioned, and the reality of the Labroidei has been challenged for several reasons. One is that none of the characters are unique to labroids (in fact, a whole suite of pharyngeal jaw features are found in the quite distantly related Beloniformes); another is that not all labroids present all the characters. In addition, characters supporting the Labroidei that are independent of the pharyngeal jaw apparatus, and perhaps less strongly influenced by selective forces related to food processing, have eluded detection. Given these challenges, it isn't surprising that recent molecular studies have failed to uphold the Labroidei as a natural group.

Nonetheless, this chapter considers two of the traditional labroid families, the cichlids and surfperches. Surfperches are temperate, almost entirely marine fishes found only in the northern Pacific, and are represented by 13 genera and 24 species. Cichlids are mostly tropical freshwater fishes, with a distribution on fragments of the supercontinent of Gondwana. There are about 105 genera of cichlids and 1,405 described species, although some estimates place the total number of cichlid species to be in excess of 2,500 if a full accounting is made of the exceptional species diversity in the three African Great Lakes. Different geologic processes and time scales have shaped these three lakes and their species flocks. Two of the lakes, Malawi and Tanganyika, formed in a rift created by plate movements that are slowly ripping apart the African continent. Lake Malawi is roughly 700,000 years old and contains 500–1,000 cichlid species; Lake Tanganyika is 9–12 million years old and contains about 200 cichlid species. Lake Victoria, formed by processes of mountain building that blocked the flow of rivers draining eastern Kenya, was probably entirely dry as recently as 12,400 years ago, leaving precious little time for the subsequent evolution of its 500 or so haplochromine cichlid species from a single ancestral species.

Evolutionary biologists have been intrigued by the question of how so many cichlid species evolved together in African lakes. Clearly, the ability of cichlids to finely partition resources provides some explanation, but the lakes themselves also play a role. Lake Victoria is relatively shallow and turbid, with few rocky microhabitats along its shoreline, but the two rift lakes are clear and deep, with abundant patches of rocky microhabitat scattered along their shores. Within Tanganyika, there are three distinct communities: the pelagic, containing six fish species; the benthic, with 80 fish species; and most diverse, the littoral, with 207 species of fishes. Most of the species diversity is restricted to inshore regions. Malawi's piscine endowment is similarly biased; so species poor are the pelagic waters in comparison with the littoral rocky communities that two zooplanktivorous species of the genus Diplotaxodon make up 71% of the open-water fish biomass. In Malawi and Tanganyika, populations in rocky littoral habitats separated by sandy bottom and deepwater barriers wider than 1.2 mi (2 km) exhibit little or no gene flow. Thus, a model of microallopatric speciation may be appropriate for the rift lakes, whereby the numerous and fragmented littoral rocky habitats, coupled with attributes of some of the cichlids, such as

resource specialization and adherence to circumscribed territories, have fostered explosive speciation. Another speciation mechanism, sexual selection, has been considered most important in Victoria due to its paucity of isolated microhabitats, and may also be important in the rift lakes.

Age differences between the lakes are also manifest in the cichlid species flocks. The two younger lakes, Malawi and Victoria, contain relatively more homogenous assemblages of strictly mouth-brooding cichlids. In contrast, Lake Tanganyika contains a very diverse assemblage of both mouth brooders and substrate spawners descended from numerous colonization events. In a 1998 paper, Sturmbauer contrasted the relatively young lake Victoria species flock, which lacks extreme morphotypes and has many intermediate species, with the ancient Lake Tanganyika flock, characterized by few intermediates and high morphological distances between species, and proposed that the two lakes represent opposite ends of a species flock evolutionary continuum. He suggested that in older lakes with mature flocks (as in Tanganyika), very diverse communities sharing most of their species will predominate, because dispersal events (facilitated by lake level fluctuations) have, over long stretches of time, mixed together species that arose in isolation. Consequently, lesser competitors in shared niches will have alternately diverged or perished.

Despite the present diversity of cichlids, both cichlids and surfperches are poorly represented in the fossil record. Fossil surfperches are first known from the upper Miocene epoch (5–10 million years ago), from the Monterey Formation in California. Only a few species of fossil cichlids are known, the earliest of which are 45 million years old (Eocene epoch) from Tanzania, East Africa. Cichlid material from Maranhao, Brazil, may also date from the Eocene, and putatively cichlid material of similar age has been found in Vicenza, Italy. If, as many researchers suggest, the present geographic distribution of cichlids is an artifact of their being widely distributed on the supercontinent of Gondwana, then cichlids must be at least 130 million years old, leaving an inexplicable gap of 85 million years in the fossil record. This has led some to argue that cichlids are actually a younger group that has dispersed across marine barriers to achieve their present distribution, an argument supported by the ability of several cichlid species to survive in sea water and the fact that cichlid distribution is not strictly Gondwanan.

Physical characteristics

Surfperches are relatively deep bodied, laterally compressed fishes with an undivided series of lateral line scales. They achieve lengths of 17.5 in (45 cm). All surfperches have cycloid scales, a deeply forked caudal fin, and three anal fin spines. Most species have scales extending onto the dorsal fin. Although many species are uniformly silvery, others have blue, black, or reddish stripes and bars. Cichlids are more variable, presenting both cycloid and ctenoid scales, a divided lateral line scale series (except in the African riverine genera Teleogramma and Gobiocichla), numerous fin shapes and lengths (the smallest species is 1 in [2.5 cm], while the largest is 36 in [91.4 cm]), and anywhere from three to 15 anal fin spines. Cichlids are also unusual in that they have only a single nostril on each side of the head, unlike most teleosts, which have two pairs of nostrils.

Cichlids exhibit an impressive range of morphological diversity: there are dinner plate–shaped discus and cigar-shaped pike-cichlids, horse-faced Tropheus that scrape algae from rocks, and canine-endowed Cichla that voraciously prey on other fishes. A diversity of tooth morphologies in both the oral and pharyngeal jaws allow cichlids to utilize every conceivable source of food. Cichlids can be drab colored or come in brilliant hues, and many exhibit magnificent color patterns that are rivaled only in coral-reef fishes. Despite their variability, however, cichlids share numerous distinctive morphological characters supporting the family as a natural group derived from a common ancestor. For instance, all cichlids have a transversus dorsalis muscle partitioned into four parts, a functionally decoupled premaxilla and maxilla, microbranchiospines on the outer faces of the gill arches, and an expanded head of the fourth epibranchial.

Distribution

Surfperches are distributed in coastal areas of the North Pacific: three species are found around Japan and Korea, and 21 species are found in North America from Alaska to the Baja Peninsula. One species, the shiner perch (Cymatogaster aggregata), enters brackish and fresh waters. Another species, the tule perch (Hysterocarpus traskii) is entirely confined to freshwater lakes and rivers in California.

Cichlids are distributed in the tropical and subtropical regions of most Gondwanan fragments, including much of South America and Africa, Madagascar, India, and Sri Lanka. They also occur naturally in Syria, Iran, Israel, Central America, North America (Texas), and the West Indies. Human introductions have led to the establishment of numerous cichlid species in localities outside their natural range. Owing to their popularity in aquaculture, the tilapiines in particular have been spread around the globe, often with devastating consequences for endemic fishes. Various tilapiines now thrive in the fresh waters of Madagascar, Mexico, Florida, and much of Southeast Asia, as well as the coastal waters of southern California.

Habitat

Surfperches are mostly restricted to inshore marine environments. Many species are found in the surf near sandy beaches, but members of the family also frequent sea-grass beds, rocky outcroppings, and piers. Less frequently, surfperches are known to enter brackish and fresh waters, and one species lives its whole life in lakes and rivers.

Cichlids also exhibit a wide salinity tolerance, and some species are found in brackish and marine waters. Some cichlids are capable of withstanding rather extreme conditions. For example, some Oreochromis species live in high-temperature, high-alkalinity salt lakes in Kenya and Tanzania. Most cichlids are freshwater fishes, however, and members of the family can be found in most every conceivable freshwater habitat within their range, including open waters of lakes, oxygen-deprived depths, rocky inshore areas, aquatic plant beds, swamps, small streams, and large rivers, including rapids habitats.

Behavior

Surfperches are unusual among marine teleosts in that they do not go through a planktonic dispersal stage as eggs or larvae; they are somewhat large when they are born and stay in the general vicinity as they mature. Many cichlids, especially those that occupy specialized lacustrine habitats, behave similarly. Although most cichlids do not defend feeding territories, some cichlids in the African Great Lakes do defend separate feeding and breeding territories. Those that defend feeding territories are predominantly algae feeders, and some herbivorous species subvert such territoriality by forming large schools that barrage an algal mat with a few individuals at a time, diluting the aggression of the territory holder so that algae can be stolen. In captivity, the territoriality and aggression of many cichlids has given the family a particular notoriety among aquarists.

In some cichlids, older siblings assist their parents in guarding new clutches of fry, an investment that can be explained evolutionarily because it increases the share of both the parents' and helpers' genes in the next generation. Consider, however, the few examples of cichlids that help guard the offspring of another species of cichlids, a behavior that at first defies explanation. One tantalizing explanation for such behavior on the part of the moga (Cichlasoma nicaraguense), males of which sometimes help guard the fry of the guapote (C. dovii), is that larger numbers of piscivorous C. dovii help to increase the reproductive success of C. nicaraguense by preying upon and reducing the numbers of poor man's tropheus (Neetroplus nematopus), a nest-site competitor of the helper species. This interpretation, while intriguing, is still controversial.

Feeding ecology and diet

Surfperches feed variously on shrimps, amphipods, crabs, and other crustaceans, as well as mollusks and worms. To feed on such organisms, many surfperches take indiscriminate bites out of the algae and debris found on the bottom, and then winnow out their invertebrate prey within the oropharyngeal cavity, spitting out the remainder. The small kelp perch (Brachyistius frenatus) feeds largely on ectoparasites picked off other fishes, and several other surfperches supplement their regular diets by engaging in such cleaning activities.

Cichlid feeding ecologies are extravagantly diverse, and may partly explain the species diversity within the family. Although most cichlids can opportunistically feed on a wide range of foods, they are also specialized to feed on certain types of food with particular efficiency. Of course, many cichlids specialize in hunting other fishes and eating them whole. Tilapia is the only genus of African cichlid to specialize on phytoplankton, by collecting the particles (with the assistance of sievelike gill rakers for filtering) in balls of mucous secreted in the mouth and then swallowing them. Deposit feeders take a very similar approach, but with sedimented phytoplankton and even disintegrated hippopotamus droppings. Cichlids who feed on epilithic algae, or aufwuchs, scrape the algae from rocks, typically employing multiple rows of fine teeth used like a file. Periphyton feeders scrape algae off living plants. For example, the giant haplochromis Hemitilapia

oxyrhynchus in Malawi feeds by placing the grasslike leaves of the plant Vallisneria between its jaws and nibbling off the algae without damaging the leaf. Singularly robust dentition characterizes leaf choppers, while mollusk feeders have large pharyngeal bones covered with flat, stocky teeth to crush shells. Labidochromis vellicans of Malawi, a benthic arthropod feeder, has very long, sharp, outward pointing teeth that resemble forceps, and uses them to pluck insects from the substrate. Alternatively, the greenface sandsifter (Lethrinops furcifer) of Malawi has a pointed, protractile mouth and sievelike gill rakers. It rams its head into the sand, filling the buccal cavity, then separates out and swallows insect larvae by expelling the sand across the gill rakers and through its opercular openings. Some species have developed protractile mouths specially suited for inhalant feeding on zooplankton. There exist fin-nipping feeders, and in Victoria and Malawi, species that feed on the eggs and larvae of other mouth brooders. Many species have acquired large molariform teeth on the pharyngeal jaws for crushing the shells of snails. Additionally, in all three African Great Lakes, cichlids with differing tooth morphologies have evolved to feed exclusively on the scales of other fishes; some even mimic the color patterns of their prey to avoid detection.

Interesting selective forces are at work within the scale-feeding Lake Tanganyika genus Perissodus. To a greater or lesser degree, all seven species exhibit laterally asymmetrical mouths that are angled either to the right or left, and this trait has a genetic basis. Left-handed individuals nip scales off the right flank of their prey, and vice versa for right-handed individuals. Incredibly, the differential alertness of prey species appears to exert selective pressure on the scale eaters that acts to maintain about equal numbers of left- and right-handed individuals within a population. A study on Perissodus microlepis found that whenever one or the other form becomes significantly less abundant, prey species become more vigilant about watching for scale eaters from the side favored by the more abundant form. In this way, the less-abundant form is conferred a selective advantage, and the genetic polymorphism responsible for the two forms is maintained.

Reproductive biology

Embiotocids are viviparous (give birth to live young), and males have a thickened anterior portion of the anal fin that aids in internal fertilization. They display elaborate courtship behaviors, reminiscent of a small cross-section of the varied courtship behaviors found in cichlids. Some cichlids, for example, members of the genera Crenicara, Sarotherodon, and Etroplus, are capable of changing sex. When a group of females finds themselves without access to a male, the dominant female is able to generate testicular tissue sufficient to fertilize the eggs of the remaining females.

Primitively, cichlids likely formed monogamous pairs, in which both parents guarded eggs laid on the substrate. Cichlids exhibiting this behavior include the Indian etroplines, most Central American taxa, many South American taxa (such as Pterophyllum and Symphysodon), as well as several African groups (including Hemichromis and the lamprologines). Some cichlids have evolved polygamy and mouth brooding as embellishments of the original reproductive mode. Mouth brooders allow the eggs and young to develop inside the safety of the buccal cavity of one or both parents. As the young mature, they make feeding excursions outside, but quickly retreat into the adult's mouth at the first sign of danger. It is fascinating that following egg deposition, females of some mouth-brooding species collect the eggs into their mouths with such alacrity that males do not have time to fertilize them externally. On the anal fin of many such males, however, are conspicuously colored spots, called egg dummies, which bear a remarkable resemblance to the actual eggs. The female notices these spots and nips at them (in an apparent attempt to collect them into her mouth, some have argued), and the male releases sperm at the same time. Thus the eggs are fertilized inside the mouth of the female.

In one instance, a noncichlid has devised a means of capitalizing on the mouth-brooding habit of cichlids at their expense. Synodontis multipunctatus, a mochokid catfish, is a brood parasite on several species of mouth-brooding cichlids in Lake Tanganyika. Catfish eggs are concealed among the cichlid eggs during spawning, and are then taken into the mouth of the adult cichlid. As development proceeds, the young catfishes devour the cichlid fry from the safety of the parental

buccal cavity, so that ultimately the cichlid parents find themselves caring for a small brood of catfish and none of their own progeny!

Many cichlids expend enormous energy in altering their surroundings prior to reproduction. Elaborate sand nests, in the form of pits or cone-shaped mounds, are constructed by the males of some cichlid species for spawning. Some nest mounds are enormous, and require many days work by the male, moving sand one mouthful at a time. In certain species, lekking occurs: males build their nests in aggregations of various sizes. In Lake Malawi, male Copadichromis eucinostomus come together in groups as large as 50,000 individuals, stretched over several miles of sand, each guarding a coneshaped nest. In Lake Tanganyika, numerous species from the tribe Lamprologini take advantage of abundant snail shells on the lake bottom as places of refuge and spawning sites. Neolamprologus callipterus, a haremic species, is noteworthy in that the males are dramatically larger than the females (as much

30 times by weight), and only females occupy shells during spawning. Selection seems to maintain this size dimorphism because males need to be large enough to carry shells to their territories, while females need to be small enough to spawn inside the shells.

Conservation status

Although none of the surfperches are listed by the IUCN, hundreds of cichlid species are either extinct or in great peril. There are 133 cichlids on the IUCN Red List, 44 of which are listed as Extinct and five of which are listed as Extinct in the Wild. Of the 37 Critically Endangered cichlids, all are from Africa or Madagascar, and most are from either Lake Barombi Mbo in Cameroon or the East African lakes Victoria, Nabugabo, Kanyaboli, and Nawampasa. Humans are responsible for the plights of these fishes, which have declined due to the introduction of exotic species, pollution from industrial sources and sewage, sedimentation related to deforestation, and overfishing. The story of Lake Victoria is emblematic in this regard, as hundreds of species have been affected by the extensive degradation of the lake's ecosystem, and thus is considered here in some detail.

Gill nets were introduced to fishermen on Lake Victoria in 1905 to catch the endemic tilapiine cichlids Oreochromis esculentus and Oreochromis variabilis. Increasing fishing activity, aided by gill nets, quickly led to declines in catches of numerous species, including the tilapiines, catfishes, and lungfishes. By the 1950s, endemic tilapia had been all but wiped out, so the Nile perch (Lates niloticus) and four nonnative tilapiine species were introduced: Tilapia zilii, T. melanopleura, Oreochromis niloticus, and O. leucostictus. Gill-net fisheries had since shifted to endemic catfishes, characins, cyprinids, and mormyrids, and as those stocks declined, fishermen were forced by the 1970s to shift their focus toward the abundant haplochromine cichlids and the pelagic cyprinid Rastrineobola argentea. Beach seines, which had been introduced to the region during the 1960s, exacerbated the problem of overfishing by disrupting the littoral spawning nests of tilapiine and haplochromine cichlids. Soon after a haplochromine trawl fishery was established in Tanzania, and a factory was built to convert the catch into chicken feed, the haplochromine fishery began its precipitous collapse. This was in the late 1970s, and was coincident with a population explosion of the much-maligned Nile perch. Lake Victoria fisheries were on the verge of total collapse, but were revitalized by the now-abundant Nile perch, supplemented by Rastrineobola and Oreochromis niloticus.

Small, bony haplochromines were not valued highly by local fishers, so creative schemes were concocted for utilizing them. Early on, it was suggested that haplochromines could be trawled and used as manure; later efforts at canning haplochromines as fish meal for livestock were hampered by the fact that the can was worth more than its contents. In areas where haplochromine trawling was implemented, however, populations declined dramatically. Their biology helps to explain why. Haplochromines are mouth brooders, and females produce a relatively small number of eggs. As narrow specialists with low-standing stocks and a low reproductive potential, they are peculiarly susceptible to collapse when nonselective fishing methods like trawling are used.

Although numerous factors, including overharvesting, appear to have precipitated the collapse of the haplochromine fishery, strong evidence implicates the Nile perch. In Mwanza Gulf, which was continuously surveyed during the 1980s, the Nile perch boom documented at the beginning of the decade was immediately followed by the total collapse of open-water haplochromine stocks. Haplochromines were selectively eaten until they were exhausted. Once Nile perch had colonized a part of the lake, the larger and less common haplochromine species were first to disappear there, especially those species with the most habitat overlap with Nile perch.

Another factor that has played a significant role in haplochromine cichlid collapse is eutrophication. The causes of Lake Victoria's eutrophication are numerous: deforestation, urban and industrial development around the shore, a rise in lake level, and even positive feedback from post haplochromine collapse food-web alterations (many haplochromines were specialized phytoplankton feeders and kept blooms in check). Since 1960, the lake's primary productivity has more than doubled, and more than half the bottom area of the lake is now devoid of oxygen below 98 ft (30 m). Drinking water for the human population on the lake's shores is now threatened by toxic blue-green algae blooms. In addition, the fact that large Lates cannot be sun dried like haplochromines, but instead require smoking over a wood fire, has accelerated deforestation and sedimentation in the basin, as the Nile perch fishery has expanded.

Eutrophication further threatens Lake Victoria's haplochromines in a very unexpected way. In a 1997 paper, Seehausen and collaborators argued that the decreased water transparency brought about by eutrophication has caused rock-dwelling cichlid declines by eroding between-species mating barriers. They point out that among the African Great Lake basins, only those lakes with clear water have given rise to cichlid species flocks. The sympatric haplochromine cichlids of Lake Victoria lack postmating reproductive barriers among closely related species, and have historically avoided hybridization through mate choice; this barrier is now breaking down as turbidity prevents females from recognizing males of their own species. Males of similar species are always manifestly distinct in coloration, and in experiments with monochromatic light, females lose their ability to discern conspecifics. Within different regions of the lake, Haplochromis color morphs behave as distinct species where the water is clear, and blend into homogenous hybrid populations where the water is cloudy.

Significance to humans

Both cichlids and surfperches are sought after by humans as sources of food. Tilapiine cichlids are easy to culture artificially, and so have been introduced around the world in fish-farming ventures. They supply an important source of protein to many human populations. However, exotic tilapiines have also adversely affected native fish populations in regions where they have been introduced by humans. Cichlids are enormously popular in the aquarium trade, and help support local economies in parts of the Americas and Africa through revenues from wild-caught fish exports. Numerous strains of certain species are also cultivated in captivity.

Species accounts

List of Species

Agassiz's dwarf cichlid

Apistogramma agassizii

family

Cichlidae

taxonomy

Geophagus (Mesops) agassizii Steindachner, 1875, Curupira, Codajas, Rio Poti de Sao Joao, Lago Maximo, and Lago Manacapuru, Brazil.

other common names

German: Agassiz Zwergbuntbarsch.

physical characteristics

Maximum length 2 in (5 cm). Dorsal and anal fins somewhat elongate, caudal fin spade shaped. Head somewhat rounded. Female coloration is lemon yellow; males brilliantly colored with yellows and blues anteriorly, a dark midlateral band, and red, black, and white bands on posterior fins.

distribution

Amazon basin along the Amazon River from Peru to the Capim River in Brazil.

habitat

Clear, black, and whitewater rivers.

behavior

Males exhibit ritualized behaviors in defense of their territories; females in the harem of a single male compete for his attention.

feeding ecology and diet

Feeds on aquatic macroinvertebrates.

reproductive biology

Eggs laid in caves, or in flowerpots in aquaria; they hatch in about four days. Practices harem polygyny.

conservation status

Not listed by the IUCN.

significance to humans

Owing to its brilliant colors and peaceable demeanor, this fish is popular in the aquarium trade.

Giant cichlid

Boulengerochromis microlepis

family

Cichlidae

taxonomy

Tilapia microlepis Boulenger, 1899, Lake Tanganyika at Moliro, Democratic Republic of the Congo, Africa.

other common names

English: Yellowbelly cichlid; German: Riesenbuntbarsch; Swahili: Kuhe.

physical characteristics

Maximum length 25.6 in (65 cm); largest African cichlid. Background color yellowish, with numerous dark but faint vertical bars. Four dark blotches along middle of flanks. Caudal fin lunate.

distribution

Widely distributed in Lake Tanganyika, East Africa.

habitat

Deeper water over sand as well as open water, enters shallower waters to breed.

behavior

Cruises open waters in pursuit of schools of small fishes.

feeding ecology and diet

Feeds on smaller fishes.

reproductive biology

Substrate spawners, uses rocks or abandoned nests of other cichlids to deposit eggs. Both parents aggressively guard fry, have even been known to attack scuba divers who approached too close to a nest. Lays 5,000–12,000 eggs during spawning; eggs hatch in about three days. Some evidence suggests that pairs do not feed again after spawning, and spawn only once in a lifetime.

conservation status

Not listed by the IUCN.

significance to humans

Popular sport fishes with excellent tasting flesh.

Trout cichlid

Champsochromis caeruleus

family

Cichlidae

taxonomy

Paratilapia caerulea Boulenger, 1908, Lake Malawi.

other common names

German: Forellen-Cichlide; Nyanja: Ndunduma.

physical characteristics

Maximum length 12.6 in (32 cm). Large, predatory cichlid with slender body. Dorsal, anal, and pelvic fins somewhat elongate in adults. Immature males and females silver gray, with dark band running obliquely along uppermost part of body. Breeding males acquire brilliant greenish blue coloration, and edges of the dorsal and anal fins become orange.

distribution

Widely distributed in Lake Malawi, East Africa.

habitat

Inshore waters to depths of 180 ft (55 m).

behavior

Juveniles school together, but adults usually cruise solitarily.

feeding ecology and diet

Feeds on smaller fishes.

reproductive biology

Mouth brooder. Male forms a pit over sandy substrate. Female lays eggs in the pit and then collects them; eggs are fertilized in the female's mouth.

conservation status

Not listed by the IUCN.

significance to humans

Locals occasionally catch these fish using baited hooks.

Speckled pavon

Cichla temensis

family

Cichlidae

taxonomy

Cichla temensis Humboldt, 1821, Rio Temi, Venezuela.

other common names

English: Peacock bass, tucunare; German: Humboldtcichlide; Spanish: Pavón.

physical characteristics

Maximum length 39 in (99 cm); perhaps the world's largest cichlid. Elongate with large head, has superficial appearance of a bass. Spinous and soft-rayed dorsal fin subdivided. Background color yellow green to tan, with three dark vertical bars and a series of horizontal rows of cream-colored spots. Ocellus on caudal fin; red on pelvic, anal, and lower lobe of caudal fins. Males acquire nuchal hump during spawning.

distribution

Amazon Basin in Rio Negro and Rio Uatumã systems; Orinoco basin in Venezuela and Colombia; introduced in Florida and Texas.

habitat

Along banks of main river channels over sand and rocks, and in deeper inshore waters of lagoons.

behavior

Voracious predators; in aquaria, they ignore any fishes that are too large to swallow.

feeding ecology and diet

Feeds on other fishes.

reproductive biology

Monogamous substrate spawners. Both parents care for eggs and young. Eggs may number up to 4,000, and are laid on logs, rocks, or in excavated pits.

conservation status

Not listed by the IUCN.

significance to humans

Popular sport and food fishes. Also found in the aquarium trade.

Millet

Crenicichla alta

family

Cichlidae

taxonomy

Crenicichla alta Eigenmann, 1912, Gluck Island, Guyana.

other common names

English: Spangled pike cichlid.

physical characteristics

Maximum length 6.3 in (16 cm). Elongate, pikelike, with pointed snout. Lower jaw extends beyond upper. Color grayish on flanks, with dark stripe running from tip of snout to caudal fin. Abdomen rose colored, cheek yellow. Ocelli on caudal fin and shoulder; dorsal, anal, and caudal fins have black and white edges.

distribution

Rio Branco River drainage, Brazil, and Essequibo River drainage, Guyana.

habitat

Rivers and streams.

behavior

Juveniles school together, adults are solitary.

feeding ecology and diet

Feeds on smaller fishes.

reproductive biology

Spawns in caves, which males dig into the bank. Both parents care for eggs and fry.

conservation status

Not listed by the IUCN.

significance to humans

Occasionally found in the aquarium trade.

No common name

Paralabidochromis chilotes

family

Cichlidae

taxonomy

Paratilapia chilotes Boulenger, 1911, Jinja, Ripon Falls, Uganda.

other common names

German: Viktoria-Wulstlippen-Maulbrüter.

physical characteristics

Maximum length 5.8 in (14.8 cm). Elongate, unicuspid, forward-directed teeth used like forceps to capture insect larvae. Lips dramatically swollen and enlarged. Color pattern varies geographically; most populations are yellow-gray over most of body. Males with green and blue on flanks, orange on dorsal, anal, and caudal fins, and chest. Females sometimes exhibit piebald coloration.

distribution

Lake Victoria, East Africa.

habitat

Sheltered inshore waters with rocky bottom to 55.8 ft (17 m) depth

behavior

In aquaria, observed digging under overhanging rocks for prey. Presses large lips against cracks in rocks when feeding. Not as territorial as many other haplochromines.

feeding ecology and diet

Feeds mainly on mayfly larvae, though also eats larvae of Trichoptera (caddisflies) and Diptera (true flies).

reproductive biology

Mouth-brooder.

conservation status

Listed as Vulnerable by the IUCN.

significance to humans

Found in the aquarium trade; one of the Lake Victoria haplochromines that has survived the Nile perch boom and other perturbations that have befallen the lake.

No common name

Lepidiolamprologus kendalli

family

Cichlidae

taxonomy

Lamprologus kendalli Poll and Stewart, 1977, Lake Tanganyika, northwest of Mutondwe Island, Zambia.

other common names

German: Kendalls Tanganjikasee-Buntbarsch.

physical characteristics

Maximum length 6.3 in (16 cm). Elongate and torpedo shaped. Dark background color, with white blotching on head and fins, and white blotches forming several almost continuous horizontal bands on flanks. Hints of blue on face, pectoral fins yellowish.

distribution

Southern part of Lake Tanganyika, East Africa.

habitat

Shallow rocky areas as well as deeper waters, up to about 148 ft (45 m).

behavior

Adults are solitary, and cover large distances in search or prey.

feeding ecology and diet

Feeds on other fishes.

reproductive biology

Substrate spawner. Females may release up to 500 eggs. In the wild, spawns at a depth of 148 ft (45 m) over a rocky bottom covered with thick sediment.

conservation status

Not listed by the IUCN.

significance to humans

Exported for the aquarium trade.

Ngege

Oreochromis esculentus

family

Cichlidae

taxonomy

Tilapia esculenta Graham, 1928, Kenya, Lake Victoria.

other common names

None known.

physical characteristics

Maximum length 19.7 in (50 cm). Relatively deep bodied, with small head. Color olive-brown to dull green, becoming whitish ventrally. Breeding males become red dorsally and black ventrally, except that dorsal fin is also black.

distribution

Lake Victoria, Lake Nabugabo, Lake Kioga, Lake Kwania, the Victoria Nile above Murchison falls, and the Malawa River. Also Lake Gangu, west of Lake Victoria. Introduced into Tanzanian and Ugandan reservoirs.

habitat

Inshore waters with aquatic vegetation when young, move into open water as adults, to depths of 164 ft (50 m). Found over muddy bottoms.

behavior

Adults school together in open water, following plankton blooms.

feeding ecology and diet

Plankton feeder, follows diatom blooms in lakes. Secretes mucous in the mouth that helps trap plankton, forming a bolus for swallowing.

reproductive biology

Mouth brooder; fertilization takes place in female's mouth. Spawns year round. Males aggregate around spawning grounds, where they occupy basin-shaped nests and defend a small territory. Once eggs are fertilized, females move to weed beds with the brood.

conservation status

Listed as Vulnerable by the IUCN.

significance to humans

Historically an important food fishery in Lake Victoria, but was overfished to the point of commercial extinction in the lake, where introduced tilapiines now predominate.

Freshwater angelfish

Pterophyllum scalare

family

Cichlidae

taxonomy

Zeus scalaris Lichtenstein, 1823, Brazil.

other common names

English: Black angelfish, longfin angelfish, veil angelfish; French: Poisson ange, scalaire; German: Dumerils, Perlscalar, Segelflosser; Spanish: Pez angel.

physical characteristics

Maximum length 3 in (7.5 cm). Very deep bodied and laterally compressed, with diamond-shaped body. Dorsal, anal, and

pelvic fins very elongate. Adults silvery in color with four dark vertical bars; juveniles have seven bars.

distribution

Widely distributed in the Amazon basin; found in Peru, Colombia, and Brazil in the Ucayali, Solimões and Amazonas Rivers. Also in the rivers of Amapá, Brazil, the Oyapock in French Guiana, and the Essequibo River in Guyana.

habitat

Lakes, swamps, and flooded forests with dense aquatic vegetation and minimal current.

behavior

Peaceable, gregarious fishes that take refuge in aquatic vegetation.

feeding ecology and diet

Feeds mainly on benthic crustaceans, including shrimps, prawns, and Artemia nauplii.

reproductive biology

Forms monogamous pairs. Female spawns on thick plant leaves, and both parents care for eggs and young. Male and female nibble at eggs to release wrigglers about a day and a half after spawning, and may move brood to a pit in the substrate.

conservation status

Not listed by the IUCN.

significance to humans

Exceedingly popular in the aquarium trade, with millions of specimens sold every year; numerous color and fin varieties have been selectively bred.

Trondo mainty

Ptychochromoides betsileanus

family

Cichlidae

taxonomy

Tilapia betsileana Boulenger, 1899, Betsileo, Madagascar.

other common names

French: Marahrely à bosse.

physical characteristics

Maximum length 9.4 in (24 cm). A fairly deep-bodied, robust fish, usually with a well-developed occipital hump. Color black or dark gray, without stripes or bars. Females appear to be speckled and lighter in color, with white blotches on the cheek.

distribution

Central highlands of Madagascar, from the Betsileo region to Lake Itasy in the Merina district.

habitat

Cool, clear, well-oxygenated waters. In rivers, often found near rapids and waterfalls; found in deep waters with rocky substrate in Lake Itasy.

behavior

Very little is known, except that the species seeks out riffles with rocky substrate.

feeding ecology and diet

Omnivorous, feeds on shrimp, aquatic insect larvae, aquatic plants, and phytoplankton.

reproductive biology

Spawns on substrate; both parents care for fry for an extended period. Reproduces from October to early November. Females lay many hundreds of eggs, preferably on large rocks.

conservation status

Listed as Critically Endangered by the IUCN.

significance to humans

Human encroachment has caused the extinction of this species in the northern part of its range, and the remaining populations are decimated.

Blue discus

Symphysodon aequifasciata

family

Cichlidae

taxonomy

Symphysodon discus aequifasciata Pellegrin, 1904, Teffé and Santarém, Brazil.

other common names

English: Brown discus, green discus; German: Blauer Diskus, Grüner Diskus, Scheibenbarsch; Spanish: Disco azul, pez disco.

physical characteristics

Maximum length 5.5 in (14 cm). Extremely laterally compressed, almost perfectly round, dinner-plate shaped. Background yellow-green to tan, with brilliant undulating streaks of turquoise blue and numerous dark vertical bands running in parallel.

distribution

Amazon basin from the Rio Putumayo in Colombia and Peru to the Rio Tocantins in Brazil.

habitat

Calm waters in and around rock crevices, roots, and aquatic vegetation.

behavior

Rather shy, schooling fish, most comfortable in or near tangles of submerged roots and branches or rock crevices. Becomes somewhat territorial during spawning.

feeding ecology and diet

Feeds on insects and insect larvae, as well as zooplankton.

reproductive biology

Forms monogamous pairs in which both parents care for the young. Females lay clutches of about 100 eggs, which hatch in roughly 60 hours, on branches or sturdy leaves. Within 4–5 days, fry become mobile and begin feeding on mucous secreted from flanks of the parents, showing preference for the male. In captivity, this mode of feeding can last as long as 8 weeks, although other foods supplement the habit.

conservation status

Not listed by the IUCN.

significance to humans

Extremely popular in the aquarium trade; many captive-bred strains exist.

Worm cichlid

Teleogramma gracile

family

Cichlidae

taxonomy

Teleogramma gracile Boulenger, 1899, Matadi, Democratic Republic of Congo, Africa.

other common names

None known.

physical characteristics

Maximum length 3.2 in (8 cm). Very elongate, cigar shaped; teeth small and unicuspid, with a few enlarged canines anteriorly. Uncharacteristically for cichlids, has single, continuous row of lateral line scales, instead of upper and lower divisions. Brownish in color, with thin red margin to dorsal fin and upper lobe of caudal fin. Females exhibit broad black margin above red patch in upper lobe of caudal fin.

distribution

Lower Congo River rapids.

habitat

Turbid, fast-flowing waters in lower Congo.

behavior

Displays extreme territoriality toward conspecifics in aquaria. Hides under rocks and in caves.

feeding ecology and diet

Feeds on aquatic macroinvertebrates.

reproductive biology

Spawns in caves, female tends to eggs. Polygynous.

conservation status

Not listed by the IUCN.

significance to humans

Very rarely exported for the aquarium trade.

Blunthead cichlid

Tropheus moorii

family

Cichlidae

taxonomy

Tropheus moorii Boulenger, 1898, Kinyamkolo, Lake Tanganyika, Africa.

other common names

English: Brabant cichlid, moorii; German: Brabantbuntbarsch.

physical characteristics

Maximum length 5.7 in (14.5 cm). Moderately deep bodied, with blunt head and snout and down-turned mouth. Bicuspid outer row of teeth, tightly spaced. Exhibits wide range of geographical color variation, with populations ranging from uniformly dark brown with vertical bars to brilliant yellow with red fins.

distribution

Patchily distributed along the southern shores of Lake Tanganyika, Africa.

habitat

Shallow inshore waters with rocky substrate.

behavior

Sometimes forms large schools composed of hundreds of individuals, which patrol rocky habitats in search of algal mats. Males are territorial, and will defend feeding territories.

feeding ecology and diet

Tears strands of algae from rocks.

reproductive biology

Maternal mouth brooder; after laying 5–17 eggs, female collects them in her mouth and positions herself near male's genital area to receive sperm. Fertilization takes place in female's mouth. Eggs hatch after about four weeks. Females continue to guard offspring for a few days after they are first released from the mouth.

conservation status

Not listed by the IUCN.

significance to humans

Popular in the aquarium trade.

Rainbow seaperch

Hypsurus caryi

family

Embiotocidae

taxonomy

Embiotoca caryi Agassiz, 1853, San Francisco Bay, California, United States.

other common names

English: Rainbow surfperch; Spanish: Perca.

physical characteristics

Maximum length 11.8 in (30 cm). Deep bodied and laterally compressed, lateral line scales uninterrupted. Red and blue stripes on body and about 10 reddish brown bars on upper part of flanks. Pelvic and anal fins reddish orange with blue edges.

distribution

Pacific coast from Cape Mendocino, California, United States, to Isla San Martin, Baja California.

habitat

Around rocky shores, reefs, piers, and kelp beds, to depths of 132 ft (40.2 m).

behavior

In the fall, gathers in large aggregations prior to breeding; females move into shallow coastal waters to give birth the following summer. Sometimes function as cleaner for other fishes by picking off parasites.

feeding ecology and diet

Feeds during day; eats mostly amphipods and copepods. Described as an oral winnower, meaning it takes mouthfuls of sand or turf, selectively removes food items, and spits out the remainder.

reproductive biology

Viviparous; nutrient and gas exchange occurs between mother and the developing embryos. Females gravid from April until mid-September, and carry 9–22 young. Juveniles born at lengths of about 2.7 in (6 cm). Males develop swelling in tissues surrounding first anal fin spine during breeding, creating an intromittent (copulatory) organ used in internal fertilization. After mating, sperm are stored for several months in female's ovarian cavity prior to fertilization.

conservation status

Not listed by the IUCN.

significance to humans

Minor commercial importance as food fishes.

Resources

Books

Barlow, G. W. "Mating Systems Among Cichlid Fishes." In Cichlid Fishes: Behaviour, Ecology and Evolution, edited by M. H. A. Keenleyside. London: Chapman & Hall, 1991.

——. The Cichlid Fishes: Nature's Grand Experiment in Evolution. Cambridge: Perseus, 2000.

Boschung, H. T., Jr., J. D. Williams, D. W. Gotshall, D. K. Caldwell, and M. C. Caldwell. The Audubon Society Field Guide to North American Fishes, Whales, and Dolphins. New York: Alfred A. Knopf, 1983.

Bugenyi, F. W. B., and K. M. Magumba. "The Present Physicochemical Ecology of Lake Victoria, Uganda." In The Limnology, Climatology and Paleoclimatology of the East African Lakes, edited by T. C. Johnson and E. O. Odada. Amsterdam: Gordon and Breach, 1996.

Eccles, D. H., and E. Trewavas. Malawian Cichlid Fishes: The Classification of Some Haplochromine Genera. Herten, West Germany: Lake Fish Movies, 1989.

Fryer, G., and T. D. Iles. The Cichlid Fishes of the Great Lakes of Africa. Edinburgh: Oliver and Boyd, 1972.

Harrison, I. J., and M. L. J. Stiassny. "The Quiet Crisis: A Preliminary Listing of the Freshwater Fishes of the World That Are Extinct or 'Missing in Action.' " In Extinctions in Near Time, edited by R. D. E. MacPhee. New York: Kluwer Academic/Plenum, 1999.

Katunzi, E. F. B. "A Review of Lake Victoria Fisheries with Recommendations for Management and Conservation." In The Limnology, Climatology and Paleoclimatology of the East African Lakes, edited by T. C. Johnson and E. O. Odada. Amsterdam: Gordon and Breach, 1996.

Kawanabe, H., M. Hori, and M. Nagoshi, eds. Fish Communities in Lake Tanganyika. Kyoto: Kyoto University Press, 1997.

Konings, A. Malawi Cichlids in Their Natural Habitat. El Paso: Cichlid Press, 1995.

——. Tanganyika Cichlids in their Natural Habitat. El Paso: Cichlid Press, 1998.

Kudhongania, A. W., D. L. Ocenodongo, and J. O. Okaronon. "Anthropogenic Perturbations on the Lake Victoria Ecosystem." In The Limnology, Climatology and Paleoclimatology of the East African Lakes, edited by T. C. Johnson and E. O. Odada. Amsterdam: Gordon and Breach, 1996.

Loiselle, P. V. The Cichlid Aquarium. Melle, Germany: Tetra-Press, 1985.

Nelson, J. S. Fishes of the World, 3rd edition. New York: John Wiley & Sons, 1994.

Patterson, C. "Osteichthyes: Teleostei." In The Fossil Record 2, edited by M. J. Benton. London: Chapman & Hall, 1993.

Paxton, J. R., and W. N. Eschmeyer, eds. Encyclopedia of Fishes, 2nd edition. San Diego: Academic Press, 1998.

Ribbink, A. J. "Distribution and Ecology of the Cichlids of the African Great Lakes." In Cichlid Fishes: Behavior, Ecology, and Evolution, edited by M. H. A. Keenleyside. London: Chapman & Hall, 1991.

Riehl, R., and H. A. Baensch. Aquarium Atlas. Melle, Germany: Baensch, 1986.

Rossiter, A. "The Cichlid Fish Assemblages of Lake Tanganyika: Ecology, Behaviour and Evolution of Its Species Flocks." In Advances in Ecological Research. Vol. 26, edited by M. Begon and A. H. Fitter. London: Harcourt Brace and Company, 1995.

Stiassny, M. L. J. "Phylogenetic Intrarelationships of the Family Cichlidae: An Overview." In Cichlid Fishes: Behavior, Ecology and Evolution, edited by M. H. A. Keenleyside. London: Chapman & Hall, 1991.

Witte, F., P. C. Goudswaard, E. F. B. Katunzi, O. C. Mkumbo, O. Seehausen, and J. H. Wanink. "Lake Victoria's Ecological Changes and Their Relationships with the Riparian Societies." In Ancient Lakes: Their Cultural and Biological Diversity, edited by H. Kawanabe, G. W. Coulter, and A. C. Roosevelt. Ghent: Kenobi Productions, 1999.

Periodicals

Arnegard, M. E., J. A. Markert, P. D. Danley, J. R. Stauffer, Jr., A. J. Ambali, and T. D. Kocher. "Population Structure and Color Variation of the Cichlid Fish Labeotropheus fuelleborni Ahl Along a Recently Formed Archipelago of Rocky Habitat Patches in Southern Lake Malawi." Proceedings of the Royal Society of London, Series B, 266(1999): 119–130.

Bernardi, G., and G. Bucciarelli. "Molecular Phylogeny and Speciation of the Surfperches (Embiotocidae, Perciformes)." Molecular Phylogenetics and Evolution 13 (1999): 77–81.

Casciotta, J., and G. Arratia. "Tertiary Cichlid Fishes from Argentina and Reassessment of the Phylogeny of New World Cichlids (Perciformes: Labroidei)." Kaupia Darmstaedter Beitraege Zur Naturgeschichte 2 (1993):195–240.

Cohen, A. S. "Extinction in Ancient Lakes: Biodiversity Crises and Conservation 40 years After J. L. Brooks." Advances in Limnology 44 (1994): 451–479.

Coulter, G. W., and R. Mubamba. "Conservation in Lake Tanganyika, with Special Reference to Underwater Parks." Conservation Biology 7, no. 3 (1993): 678–685.

Drucker, E. G., and J. S. Jensen. "Functional Analysis of a Specialized Prey Processing Behavior: Winnowing by Surfperches (Teleostei: Embiotocidae)." Journal of Morphology 210 (1991): 267–287.

Galis, F., and J. A. J. Metz. "Why Are There So Many Cichlid Species?" Trends in Ecology and Evolution 13, no. 1 (1998): 1–2.

Hori, M. "Frequency-Dependent Natural Selection in the Handedness of Scale-Eating Cichlid Fish." Science 260(1993): 216–219.

Kaufman, L. S. and K. F. Liem. "Fishes of the Suborder Labroidei (Pisces: Perciformes): Phylogeny, Ecology, and Evolutionary significance." Breviora 472 (1982): 1–19.

Liem, K. F. "The Pharyngeal Jaw Apparatus of the Embiotocidae (Teleostei): A Functional and Evolutionary Perspective." Copeia 2 (1986): 311–323.

Murray, A. M. "The Fossil Record and Biogeography of the Cichlidae (Actinopterygii: Labroidei)." Biological Journal of the Linnean Society 74 (2001): 517–532.

——. "The Oldest Fossil Cichlids (Teleostei: Perciformes): Indication of a 45 Million-Year-Old Species Flock." Proceedings of the Royal Society of London, Series B, 268(2001): 679–684.

Ogutu-Ohwayo, R. "The Decline of the Native Fishes of Lakes Victoria and Kyoga (East Africa) and the Impact of Introduced Species, Especially the Nile Perch, Lates niloticus, and the Nile Tilapia, Oreochromis niloticus." Environmental Biology of Fishes 27 (1990): 81–96.

Poll, M. "Classification des Cichlidae du Lac Tanganika: Tribus, Genres et Espèces." Académie Royale de Belgique. Mémoires de la classe des sciences 45 (1986): 1–163.

Reinthal, P. N., and M. L. J. Stiassny. "Revision of the Madagascan Genus Ptychochromoides (Teleostei: Cichlidae), with Description of a New Species." Ichthyological Exploration of Freshwaters 7 (1997): 353–368.

Schliewen, U. K., D. Tautz, and S. Pääbo. "Sympatric Speciation Suggested by Monophyly of Crater Lake Cichlids." Nature 368 (1994): 629–632.

Seehausen, O., J. J. M. van Alphen, and F. Witte. "Cichlid Fish Diversity Threatened by Eutrophication That Curbs Sexual Selection." Science 277 (1997): 1,808–1,811.

Stiassny, M. L. J. "The Phyletic Status of the Family Cichlidae (Pisces, Perciformes): A Comparative Anatomical investigation." Netherlands Journal of Zoology 31, no. 2(1981): 275–314.

——. "Cichlid Familial Intrarelationships and the Placement of the Neotropical Genus Cichla (Perciformes, Labroidei)." Journal of Natural History 21 (1987): 1311–1331.

Stiassny, M. L. J., and J. S. Jensen. "Labroid Intrarelationships Revisited: Morphological Complexity, Key Innovations, and the Study of Comparative Diversity." Bulletin of the Museum of Comparative Zoology 151, no. 5 (1987): 269–319.

Streelman, J. T., and S. A. Karl. "Reconstructing Labroid Evolution with Single-Copy Nuclear DNA." Proceedings of the Royal Society of London, Series B, 264 (1997): 1,011–1,020.

Sturmbauer, C. "Explosive Speciation in Cichlid Fishes of the African Great Lakes: A Dynamic Model of Adaptive Radiation." Journal of Fish Biology, Supplement A, 53 (1998): 18–36.

Thompson, A. B., E. H. Allison, and B. P. Ngatunga. "Distribution and Breeding Biology of Offshore Cichlids in Lake Malawi/Niassa." Environmental Biology of Fishes 47(1996): 235–254.

Turner, G. F., O. Seehausen, M. E. Knight, C. J. Allender, and R. L. Robinson. "How Many Species of Cichlid Fishes Are There in African Lakes?" Molecular Ecology 10 (2001): 793–806.

Robert Schelly, MA