Butterfishes

_{-- B u t t e r f i s h e s --} _{click on the question number for the answer}
Q 1.
	There is a small fish known as the “butterfish” that appears off the New England coast during the late summer or early fall. To what family does it belong and what makes it smell different from other fish in the same area?
Q 2.
	What is the small blue-and-silvery fish that is often seen swimming under a Portuguese man-of-war?
Q 3.
	What is the small pilotfish that swims under the Portuguese Man-of-War?
Q 4.
	We have tried unsuccessfully to keep Nomeus, the Portuguese man-of-war fish, alive in a 52-gallon aquarium. Can this fish be kept alive in captivity? Also, is it possible to catch small flyingfishes at night using nets and are they aquarium fish?
Q 5.
	What are the physiological adaptations of the Portuguese man-of-war fish, Nomeus, that render it impervious to the nematocysts of the hydroid Physalia?
Q 6.
	Are the butterfish fillets sold in California markets actually sablefish?


_{-- a n s w e r s a b o u t B u t t e r f i s h e s --}
	Q&A 1.	There is a small fish known as the “butterfish” that appears off the New England coast during the late summer or early fall. To what family does it belong and what makes it smell different from other fish in the same area? Rochester, Massachusetts
	The butterfish is a common coastal species of the family Stromateidae. Its scientific name is Poronous triacanthus. The butterfish begins to spawn in the Gulf of Maine in June, shortly after its arrival there. It is common along the central Atlantic coast as far south as the Carolinas, and is occasionally taken off Florida, but it is not common there. Concerning the reported different odor of the species, we can only quote from Fishes of the Gulf of Maine: “This is one of our best table fish, fat, oily and of delicious flavor. Experience with many fresh from the net, as well as on the table, proves the old tale to be a myth, that butterfish have a peculiar odor.” There is an extended account of this fish printed in the above work published as Bulletin 74, Volume 53 for 1953, by the U.S. Fish and Wildlife Service, and available through the Superintendant of Documents, U.S. Printing Office, Washington 24, D.C. as a bound copy for $4.25.
go back to Questions
	Q&A 2.	What is the small blue-and-silvery fish that is often seen swimming under a Portuguese man-of-war?
	This remarkable little fish is the Portuguese man-of-war fish or bluebottle fish Nomeus gronovii. This fish is always found in the company of the violently-stinging man-of-war. Although the fish is not "immune" to the man-of-war's poison in the popular sense, it enjoys protection from its enemies, as it apparently does not "trigger off" the stinging tentacles with which it may come in contact. In keeping with the beautiful clear blue color of the Portuguese man-of-war, the bluebottle fish is similarly colored on the body and fins.
go back to Questions
	Q&A 3.	What is the small pilotfish that swims under the Portuguese Man-of-War? Anna Maria, Florida
	The small fish that swims under certain jellyfish and the Portuguese Man-of-War (Physalia physalis) is called the Portuguese Man-of-War fish, blue-bottle fish or shepherd fish. The scientific name of this blue-to-purplish fish is Nomeus gronovii. It lives among the tentacles of the Portuguese Man-of-War, sharing a partnership that is beneficial to both and harmful to neither, a relationship known as symbiosis. Other small fish which swim into the tentacles of Physalia are killed by the thousands of stinging cells which it possesses. Nomeus, however, is strangely unharmed, either because under natural conditions it is immune to the stinging cells or because it is somehow not attacked by them. It has been demonstrated in the laboratory that Nomeus can under certain conditions be attacked and injured by Physalia.
go back to Questions
	Q&A 4.	We have tried unsuccessfully to keep Nomeus, the Portuguese man-of-war fish, alive in a 52-gallon aquarium. Can this fish be kept alive in captivity? Also, is it possible to catch small flyingfishes at night using nets and are they aquarium fish? Neptune Beach, Florida
	The man-of-war fish, Nomeus gronowi, can be kept alive in running seawater aquaria for as long as a few weeks but in recirculating aquaria they generally live no longer than a few days. The biggest problem seems to be that Nomeus will not accept food in an aquarium. It is possible to dipnet flyingfishes at night with the aid of a light hung above or just under the surface. Flyingfishes do not survive well in aquaria.
go back to Questions
	Q&A 5.	What are the physiological adaptations of the Portuguese man-of-war fish, Nomeus, that render it impervious to the nematocysts of the hydroid Physalia? Chicago, Illinois
	Unlike anemone fishes which have a nematocyst discharge inhibitor in their slime, Nomeus gronovii has no special protection from the nematocysts of its dangerous host, the Portuguese man-of-war, and these delicately colored fish are often massively stung. The fish does have at least one antibody in its blood, however, which helps counter the effect of the hydroid's toxin. This, coupled with a highly developed talent for avoiding the tentacles, is apparently enough to render the fish relatively safe.
go back to Questions
	Q&A 6.	Are the butterfish fillets sold in California markets actually sablefish? Oceanside, California
	The sablefish (Anoplopoma fimbria) is sometimes marketed as "butter-fish fillets" and has become the subject of an expanded United States fishery in recent years. American fishermen had been hesitant to exploit this deepwater resource, since gear investment is substantial and a lucrative home market is lacking. With establishment of a 200-mile fishing zone along United States coasts in 1976, however, Americans began to replace the Japanese and South Koreans in this enterprise and exported most of their catch to Japan. In 1979, good harvest of other fish species by the Japanese curbed the demand for sablefish, bringing United States fishing activity for this species to a near standstill. Currently, California biologists are surveying sablefish populations in the eastern North Pacific Ocean in an effort to obtain precise information on the nature and extent of the resource. The sablefish reaches a length of 3 feet and can weigh up to 40 pounds. Its firm white flesh is somewhat oily; thus, it is best eaten fresh. It is quite tasty when smoked or barbecued. Information on sablefish biology and the fishery is given in Marine Advisory Leaflet 21155, available free of charge from Extension Wildlife and Sea Grant, University of California, Davis, California 95616.
go back to Questions


	Rosenstiel School of Marine & Atmospheric Science Library University of Miami, FL USA 4600 Rickenbacker Causeway, Miami, Florida 33149 Phone: 305 421 4060 Fax: 305 421 9306 E-mail: libcirc@rsmas.miami.edu		go to the top