Toadfish

:"This article is about the fish; for the fictional television character, see Toadfish Rebecchi."Taxobox
name = Toadfishes


regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Batrachoidiformes
familia = Batrachoididae
subdivision_ranks = Genera
subdivision = Subfamily Batrachoidinae
"Amphichthys"
"Austrobatrachus"
"Barchatus"
"Batrichthys"
"Batrachoides"
"Batrachomoeus"
"Chatrabus"
"Halobatrachus"
"Halophryne"
"Opsanus"
"Perulibatrachus"
"Riekertia"
"Sanopus"
"Tharbacus"
"Triathalassothia"
Subfamily Porichthyinae
"Aphos"
"Porichthys"
Subfamily Thalassophryninae
"Daector"
"Thalassophryne"The toadfish comprise the family Batrachoididae, the only family in the ray-finned fish order Batrachoidiformes. Both the English common name and scientific name refer to their toad-like appearance ("batrakhos" is Greek for frog). There are 69 species in 19 genera, most of which are marine in distribution though some are found in brackish water and one subfamily, the Thalassophryninae, is found exclusively in freshwater habitats in South America. Toadfish are benthic ambush predators that favor sandy or muddy substrates where their cryptic coloration helps them avoid detection by their prey. The dorsal fin and gill cover spines on the toadfishes of the subfamily Thalassophryninae are hollow and will inject venom into any predator attempting to eat the fish. Its dorsal fins and opercular spines are so poisonous, that eating them may result in serious illness or death.

Toadfish are well known for their ability to "sing", males in particular using the swim bladder as a sound-production device used to attract mates. The Western Atlantic species "Opsanus tau" known as the oyster toadfish is quite widely used as a research animal, while a few species, most notably "Thalassophryne amazonica", are occasionally kept as aquarium fish.

Morphology

Toadfishes are usually scaleless, with eyes set high on large heads. Their mouths are also large, with both maxilla and premaxilla. The gills are small and occur only on the sides of the fish. The pelvic fins are forward of the pectoral fins, usually under the gills, and have one spine with several soft rays. There are two separate dorsal fins, the first smaller dorsal fin with spines; and the second larger and longer dorsal, with from 15 to 25 soft rays. The number of vertebra range from 25 to 47.

Toadfishes of the genus "Porichthys", the midshipman fishes, have photophores and four lateral lines, while the Thalassophryninae are venomous, with a total of four hollow spines (two dorsal and one on each gill-flap (opercle)) connecting to venom glands and capable of delivering a painful wound.

Distribution

Toadfish are found worldwide. Almost all are marine, but "Daector quadrizonatus" and "Thalassophryne amazonica" are known from Colombia (Atrato River) and the Amazon River, respectively.

Habits

Toadfishes are bottom-dwellers, ranging from near shore areas to deep waters. They tend to be omnivorous, eating sea worms, crustaceans, mollusks and other fish. They often hide in rock crevices, among the bottom vegetation, or even dig dens in the bottom sediments, from which they ambush their prey.

Males make the nests and guard them after the female lays the eggs. The male attracts the female by "singing", that is by releasing air by contracting muscles on their swim bladder. The sound has been called a 'hum' or 'whistle'.

Economics

Toadfish are not normally commercially exploited, however, they are taken by local fishermen as a food fish, and by trawlers where they usually end up as a source of fishmeal and oil. Some smaller toadfish from brackish-water habitats have been exported as fresh-water aquarium fishes.

References

* Nelson, Joseph S. (2006) "Order Batrachoidiformes" "Fishes of the World" (4th ed.) John Wiley & Sons, Hoboken, NJ, ISBN 978-0-471-25031-9 pp. 248-249;
* Collette, B. B. "Order Batrachoidiformes, Batrachoididae, Toadfishes." In Carpenter, Kent E. (ed.) (2002) "The living marine resources of the Western Central Atlantic Vol. 2, Bony fishes. Pt. 1 Acipenseridae to Grammatidae" Food and Agriculture Organization of the United Nations, Rome (Special publication of the American Society of Ichthyologists and Herpetologists no. 5) ISBN 9251048266 ;
* Collette, B.B. and J. L. Russo (1981) "A Revision of the Scaly Toadfishes, Genus Batrachoides, with Descriptions of Two New Species from the Eastern Pacific" "Bulletin of Marine Science" 31(2): pp. 197–233;
* Hutchins, J.B. (1976) "A revision of the Australian frogfishes (Batrachoididae)" "Records of the Western Australian Museum" 4(1): pp. 3-43;
* CBC Radio Quirks and Quarks show podcast [http://www.cbc.ca/quirks/archives/06-07/nov04.html#3 segment on unique toad fish habits] with links to primary sources.

See also

*List of fish common names
*List of fish families

External links

* [http://www.fishbase.org/Summary/FamilySummary.cfm?ID=189 FishBase entry on Batrachoididae]