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Black bullhead
The black bullhead (''Ameiurus melas'') is a species of bullhead catfish. Like other bullhead catfish, it has the ability to thrive in waters that are low in oxygen, brackish, turbid and/or very warm.〔(Black Bullhead Detailed Information – Montana Animal Field Guide )〕 It also has barbels located near its mouth, a broad head, spiny fins and no scales. It can be identified from other bullheads as the barbels are black, and it has a tan crescent around the tail. Its caudal fin is truncate (squared off at the corners).〔http://www.dnr.state.mn.us/fish/blackbullhead.html〕 Like virtually all catfish, it is nocturnal, preferring to feed at night, although young will feed during the day. It generally does not get as large as the channel or blue catfish; with average adult weights are in the one to two-pound range, and almost never as large as five pounds. It has an average length of 8-14 inches, with the largest specimen being 24 inches, making it the largest of the bullheads. It is typically black or dark brown on the dorsal side of its body and yellow or white on the ventral side.〔
Like most of the bullheads (and even the cousin flathead catfish), it has a squared tail fin, which is strikingly different from the forked tail of channel and blue catfish. It is a bottom-rover fish, meaning it is well-adapted for bottom living. It is typically dorso-ventrally flattened, and has a slightly humped back.〔http://mdc.mo.gov/discover-nature/outdoor-recreation/nature-viewing/fish/fish-adaptations〕 Its color will depend on the area where it is taken, but it generally is darker than brown or yellow bullheads. It can be distinguished from a flathead in that the black bullhead's lower lip does not protrude past the upper lip. Distinguishing it from the brown bullhead is a bit more difficult, depending on the area where they are caught, but a distinguishing detail between the two includes a nearly smooth pectoral spine on the black bullhead with the brown being strongly barbed. The anal fin also has a gray base, and the tail also has a pale bar. Also, the brown bullhead will generally have 21 to 24 soft rays through its anal fin as opposed to the black bullhead's 17 to 21. The brown bullhead is also typically mottled brown and green on top instead of the darker black. Both the black and brown bullheads can easily be distinguished from the yellow bullhead as the yellow bullhead has white barbels under its mouth.〔 Phillips, G.L, Schmid, W.D, & Underhill, J.C. (1991). Fishes of the Minnesota region. Minneapolis: University of Minnesota Press.〕
==Habitat==
Black bullheads are found throughout the central United States, often in stagnant or slow-moving waters with soft bottoms. They have been known to congregate in confined spaces, such as lake outlets or under dams. They are very tolerant fish, and are able to live in muddy water, with warmer temperatures and in water with lower levels of oxygen, which reduce competition from other fish.〔
Black bullheads also occur as an invasive species in large parts of Europe.〔Leppakoski, Erkki. Invasive aquatic species of Europe: distribution, impacts, and management. Kluwer Academic Publishers. 1998. The Netherlands. 156-162.〕
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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