Batrachoidiformes

(Toadfishes)

Class Actinopterygii

Order Batrachoidiformes

Number of families 1

Evolution and systematics

The family Batrachoididae is the only family in the order Batrachoidiformes, and is thought to be most closely related to the fishes in the order Lophiiformes containing the goosefishes, frogfishes, and deepsea anglers. It has been divided into three subfamilies: Porichthyinae (Porichthys, 14 species and Aphos, 1 species) and Thalassophryninae (Daector, 5 species and Thalassophryne, 6 species) are the most derived and are restricted to the New World; Batrachoidinae containing at least 16 genera (including Opsanus and Sanopus) and about 51 species occur worldwide.

Physical characteristics

Toadfishes are small- to medium-sized fishes with a broad, flattened head and a wide mouth that usually has barbels and/or fleshy flaps around it. The eyes are on top of the head and directed upwards. The pelvic fins are forward, in front of the pectoral fins, and have one spine and three soft rays. There are two separate dorsal fins, the first with two or three spines, and the second is long with 15 to 25 soft rays. The anal fin is somewhat shorter than the second dorsal fin. The pectoral fins are large with a broad base. The gill openings are small and are restricted to the sides of the body. Species of Porichthys have photophores (light organs) along their sides and ventral surface. Species in the subfamily Thalassophryninae have hollow, venomous spines in their first dorsal fin and opercles. Bifax lacinia has a flap with an eye spot at the end of the maxilla on each side of the mouth.

Toadfishes usually are rather drab colored, often brownish with darker saddles, bars, or spots; however, some species in the Atlantic genus Sanopus are brightly colored. Maximum size of species ranges from 2.2 in (56 mm) to at least 20.1 in (510 mm) standard length.

Distribution

Worldwide between about 51° N and 45° S along continents in marine and brackish waters, occasionally entering rivers. Several freshwater species in South America.

In the New World Pacific Ocean: the genus Porichthys occurs from southeast Alaska south to Ecuador; Aphos from Peru south to Chile; Daector from Costa Rica to Peru; and Batrachoides from Mexico to Peru. In the New World Atlantic Ocean: Porichthys occurs from Virginia south to Argentina; Opsanus from Massachusetts south to Belize; Sanopus from Yucatan, Mexico to Panama; Triathalassothia in Belize, Honduras, and Argentina; Amphichthys from Panama to Brazil; Thalassophryne from Panama to Uruguay. Species of Daector,

Thalassophryne, and Potamobatrachus occur in freshwater in South America.

In the eastern Atlantic Ocean Batrachoides, Halobatrachus, Perulibatrachus, and Chatrabus occur along the African coast. South Africa has several genera: Chatrabus, Batrichthys, and Austrobatrachus. Barchatus is found in the Red Sea and adjacent areas, Bifax in the Gulf of Oman as well as Austrobatrachus, which ranges to India. Allenbatrachus ranges from India through the Indo-Australian archipelago to the Philippines and north to Thailand. Toadfishes have not been recorded from Taiwan or Japan. The genus Halophryne occurs on the west, north, and east costs of Australia, and north to the Philippine Islands, and Batrachomoeus has the same range in Australia and ranges north through the Indo-Australian archipelago to Vietnam.

Habitat

Toadfishes rest on and bury in the substrata and are found from the shoreline down to deep water, at least to 1,200 ft (366 m). They occur in full-strength sea water, brackish water, and also freshwater. Their usual cryptic coloration allows them to blend with the subtrata where they can function as ambush predators. The species in the genus Sanopus typically live in sand depressions under coral heads.

Behavior

Toadfishes are known for their sound production resulting from the contraction of muscles on the swim bladder. Both males and females produce agonistic grunts, whereas only males make longer courtship calls, "boat whistles," or "hums."

Feeding ecology and diet

In addition to being ambush predators, toadfishes also move about feeding on invertebrates, mostly crabs, shrimps, mollusks, sea urchins, and fishes, and others take planktonic organisms from the water column.

Reproductive biology

Males prepare nests, usually in a cavity under a rock or shell, including objects discarded by humans such as cans or bottles. Males attract females by vocalizations, and then females lay large, adhesive eggs and leave the area. Males guard and fan the eggs until after hatching. The young may remain in the nest after hatching, still attached to the nest surface and even after free swimming. The plainfin midshipman has two types of males, larger nest holding ones and smaller sneaker males that dart into nests attempting to fertilize eggs of a nesting pair.

Conservation status

The IUCN lists five species of toadfishes as Vulnerable— the Cotuero toadfish (Batrachoides manglae), the whitespotted toadfish (Sanopus astrifer), the whitelined toadfish (S. green-fieldorum), the reticulated toadfish (S. reticulatus), and the splendid coral toadfish (S. splendidus). A number of species appear to have very limited distributions.

Significance to humans

Larger toadfish species are eaten, although there is no specific fishery for them. Species in the genus Allenbatrachus are occasionally collected and sold in the aquarium trade as freshwater fishes. Species in the genera Opsanus and Porichthys are used in laboratory studies. Venomous toadfishes in the subfamily Thalassophryninae can inflict pain if handled.

Species accounts

List of Species

Oyster toadfish

Opsanus tau

family

Batrachoididae

taxonomy

Gadus tau Linnaeus, 1766, Carolina, United States.

other common names

None known.

physical characteristics

The maximum size is 15 in (381 mm) standard length. There are three dorsal-fin spines, a body lacking scales, and a single subopercular spine. The inner surface of the pectoral fins has discrete glands between the upper rays, and the pectoral fin with an axillary pore behind it. The second dorsal fin has 23–27 soft rays, and the anal fin has 19–23 soft rays. The tongue, gill arches, roof of mouth and inner surface of the gill covers are light, not black, and the background color of the body is dark with no spots. The pectoral fin has definite cross bars.

distribution

Atlantic coast of the United States, from Maine to Miami, Florida.

habitat

Usually found over rock, sand, or mud, and oyster shell bottoms, often most abundant in estuaries.

behavior

This species makes a grunting noise by rubbing muscles across the swim bladder. Males use a boat-whistle call to attract females to nesting sites.

feeding ecology and diet

Feeds mainly on small crabs and other crustaceans.

reproductive biology

Males establish nesting sites from April through October. Reproductive behavior typical of the family.

conservation status

Not threatened.

significance to humans

Generally considered a nuisance when caught by fishers, but used as an experimental animal for studies involving insulin and diabetes, drug metabolism, hearing, dizziness, and motion sickness.

Plainfin midshipman

Porichthys notatus

family

Batrachoididae

taxonomy

Porichthys notatus Girard, 1854, San Francisco, California, United States.

other common names

English: Singing fish, canary bird fish.

physical characteristics

The maximum size is 15 in (380 mm) standard length. There are two spines in the first dorsal fin, and the second dorsal and anal fins are long. There are rows of photophores on the head and body, and those on the underside of the head are V-shaped.

distribution

Southeast Alaska to Baja, California, Mexico.

habitat

Usually buried in soft bottom, mud, or sand, but can be found in rocky intertidal areas during breeding season.

behavior

Like other family members it produces sound, making grunts and a hum that is a mating call. It has been demonstrated that the photophores can be used as a countershading mechanism to hide the midshipman from predators while it is foraging in the water column at night.

feeding ecology and diet

A nocturnal species that is partially buried during the day but at night rises into the water column to feed on planktonic organisms. It has been suggested that its photophores help illuminate food items. It also can function as an ambush predator, taking crustaceans and fishes while buried.

reproductive biology

Males establish nests under objects and attract females by humming. Two kinds of males are present, larger nest-holding ones and smaller sneaker males that dart into nests attempting to fertilize eggs of a nesting pair. There have been reports that the photophores also are involved in mating behavior.

conservation status

Not threatened.

significance to humans

The humming of breeding males bothers persons living in houseboats. It is used as a laboratory animal and is an important food item for seals and sea lions.

Atlantic midshipman

Porichthys plectrodon

family

Batrachoididae

taxonomy

Porichthys plectrodon Jordan and Gilbert, 1882, Galveston, Texas, United States.

other common names

None known.

physical characteristics

The maximum size is 8.6 in (218 mm) standard length. There are two spines in the first dorsal fin, and the second dorsal and anal fins are long. There are rows of photophores on the head and body, and those on the underside of the head are U-shaped.

distribution

Cape Henry, Virginia south to northern Brazil, including the Gulf of Mexico and the Caribbean Sea.

habitat

Prefers mud bottoms where it buries itself during the day

behavior

It produces both aggressive and mating vocalizations. Photophores may be used as a countershading mechanism to avoid predators while foraging in the water column at night.

feeding ecology and diet

Although some benthic invertebrates and fishes have been found in their stomachs, most of the food consists of planktonic crustaceans and larval fishes taken at night while foraging in the water column.

reproductive biology

It moves from deeper water into shallow bays and spawns in the spring and summer. The reproductive behavior is typical of the family.

conservation status

Not threatened.

significance to humans

Used as an experimental animal.

Splendid coral toadfish

Sanopus splendidus

family

Batrachoididae

taxonomy

Sanopus splendidus Collette, Starck, and Phillips, 1974, Cozumel Island, Mexico.

other common names

None known.

physical characteristics

The maximum size is 9.9 in (252 mm) standard length. There are three dorsal-fin spines; a single subopercular spine; no scales; no glands between the upper rays of the inner surface of pectoral fins; and an axillary pore present. All fins are bordered with black and orange-yellow.

distribution

Known only from off Cozumel Island, Quintana Roo, Mexico.

habitat

Usually found in sand depressions under coral heads.

behavior

Not known.

feeding ecology and diet

An ambush predator feeding on small fishes and gastropods.

reproductive biology

Not known.

conservation status

Listed as Vulnerable by the IUCN. It is known only from off Cozumel Island and thus is potentially at risk.

significance to humans

Commonly photographed by scuba divers.

Resources

Books

Breder, C. M., Jr., and D. E. Rosen. Modes of Reproduction in Fishes. Garden City, NY: Natural History Press, 1966.

Collette, B. B. "Order Batrachoidiformes, Batrachoididae, Toadfishes." In FAO Western Central Atlantic Identification Guide to Living Marine Resources of the Western Central Atlantic, edited by K. E. Carpenter. Rome: FAO, in press.

Collette, B. B., and G. Klein-MacPhee, eds. Bigelow and Schroeder's Fishes of the Gulf of Maine. 3rd edition. Washington, DC: Smithsonian Institution Press, 2002.

Eschmeyer, W. N., E. S. Herald, and H. Hammann. A Field Guide to Pacific Coast Fishes of North America. Boston: Houghton Mifflin Company, 1983.

Greenfield, D. W. "Batrachoididae." In FAO Species Identification Guide for Fishery Purposes. The Living Marine Resources of the Western Central Pacific, edited by K. E. Carpenter and V. H. Niem. Rome: FAO, 1999.

Hart, J. L. Pacific Fishes of Canada. Ottawa: Fisheries Research Board of Canada, Bulletin 180, 1973.

Hoese, H. D., and R. H. Moore. Fishes of the Gulf of Mexico, Texas, Louisiana, and Adjacent Waters. 2nd edition. College Station, TX: Texas A & M University Press, 1998.

Murdy, E. O., R. S. Birdsong, and J. A. Musick. Fishes of Chesapeake Bay. Washington, DC: Smithsonian Institution Press, 1997.

Potts, D. T., and J. S. Ramsey. A Preliminary Guide to Demersal Fishes of the Gulf of Mexico Continental Slope (100 to 600 fathoms). Mobile, AL: Alabama Sea Grant Extension, 1987.

Robins, C. R., and G. C. Ray. A Field Guide to Atlantic Coast Fishes of North America. Boston: Houghton Mifflin Company, 1986.

Periodicals

Bass, A. H. "Shaping Brain Sexuality." American Scientist 84 (1996): 352–363.

Collette, B. B. "A Review of the Venomous Toadfishes, Subfamily Thalassophryninae." Copeia 1966, no. 4 (1966): 846–864.

——. "A Review of the Coral Toadfishes of the Genus Sanopus with Descriptions of Two New Species from Cozumel Island, Mexico." Proceedings of the Biological Society of Washington 87, no. 18 (1974): 185–204.

——. "Two New Species of Coral Toadfishes, Family Batrachoididae, Genus Sanopus, from Yucatan, Mexico, and Belize." Proceeding of the Biological Society of Washington 96, no. 4 (1983): 719–724.

——. "Potamobatrachus trispinosus, a New Freshwater Toadfish (Batrachoididae) from the Rio Tocantins, Brazil." Ichthyological Explorations of Freshwaters 6, no. 4 (1995): 333–336.

Collette, B.B., and J. L. Russo. "A Revision of the Scaly Toadfishes, Genus Batrachoides, with Descriptions of Two New Species from the Eastern Pacific." Bulletin of Marine Science 31, no. 2 (1981): 197–233.

Crane, J. M., Jr. "Bioluminescent Courtship Display in the Teleost Porichthys notatus." Copeia 1965, no 2 (1965): 239–241.

Gilbert, Carter R. "Western Atlantic Batrachoidid Fishes of the Genus Porichthys, Including Three New Species." Bulletin of Marine Science 18, no. 3 (1968): 671–730.

Greenfield, D. W. "Perulibatrachus kilburni, a New Toadfish from East Africa (Teleostei: Batrachoididae)." Copeia 1996, no. 4 (1996): 901–904.

——. "Allenbatrachus, a New Genus of Indo-Pacific Toadfish (Batrachoididae)." Pacific Science 51, no. 3 (1997): 306–313.

——. "Halophryne hutchinsi: a New Toadfish (Batrachoididae) from the Philippine Islands and Pulau Waigeo, Indonesia." Copeia 1998, no. 3 (1998): 696–701.

Greenfield, D. W., and T. Greenfield. "Triathalassothia gloverensis, a New Species of Toadfish from Belize (=British Honduras) with Remarks on the Genus." Copeia 1973, no. 3(1973): 560–565.

Greenfield, D. W., J. K. L. Mee, and J. E. Randall. "Bifax lacinia, a New Genus and Species of Toadfish (Batrachoididae) from the South Coast of Oman." Fauna Saudia Arabia 14 (1994): 276–281.

Hutchins, J. B. "A Revision of the Australian Frogfishes (Batrachoididae)." Records of the Western Australian Museum 4, no. 1 (1976): 3–43.

Lane, E. D. "A Study of the Atlantic Midshipmen, Porichthys porosissimus, in the Vicinity of Port Arkansas, Texas." Contributions in Marine Science 12 (1967): 1–53.

Roux, Ch. "Révision des Poissons Marins de la Famille des Batrachoididae de la Côte Occidentale Africaine." Bulletin du Muséum National D'Historie Naturelle 2nd series 42, no. 4(1971): 626–643.

Smith, J. L. B. "The Fishes of the Family Batrachoididae from South and East Africa." Annals and Magazine of Natural History 12th series no. 52 (1952): 313–339.

Walker, H. J., and R. H. Rosenblatt. "Pacific Toadfishes of the Genus Porichthys (Batrachoididae) with Descriptions of Three New Species." Copeia 1988, no. 4 (1988): 887–904.

David W. Greenfield, PhD