Black Bullhead, Ameiurus melas
The Black Bullhead, Ameiurus melas, whose common Spanish name is bagre torito negro, is a member of the North American Catfish or Ictaluridae Family, known collectively as bagres de agua dulce in Mexico. This fish is also known as the Black Bullhead Catfish. Globally, there are 51 species in the Ictaluridae Family, of which seven belong to the genus Ameiurus. This is the only species in this family found in the freshwater systems of Mexico.
The Black Bullheads have characteristic catfish bodies with a flattened belly and a slightly humped back. They are black or dark brown dorsally and transition to golden yellow ventrally. Their anal fin has a pale base. Their fins are darker than the adjacent parts of the body. Their anal fin has 15 to 21 rays; their caudal fin is square to slightly lunate; their dorsal fin has one spine and six rays and is followed by a small adipose fin; and their pectoral fins have smooth edges. Their dorsal and pectoral fins have sharp spines which release toxic venom that is used as defense to avoid predation. Their head is large, broad, and rounded with small eyes and a lower lip that does not protrude past the upper lip. They have a short, wide, and terminal mouth equipped with sets of short, pointed, conical, and cardiform teeth set in multiple rows. There have four pairs of barbels at the corner of their mouth that are about twice as long as those near their nostrils. They have 15 to 21 gill rakers. They have no scales but are covered with 100,000 taste receptors used to locate and identify food.
The Black Bullheads are found demersal in stagnant and slow-moving freshwater bodies with soft bottoms. They are known to congregate in small confined areas in waters that range in temperature from 8oC (46oF) to 30oC (86oF). They reach a maximum length of 66 cm (26 inches) and weight of 3.6 kg (7.9 pounds). They thrive in poor water conditions, including in low oxygen, brackish, turbid, and hot waters. They are active nocturnal feeders consuming grains, plant materials, insects, dead and live fish, and crustaceans. Juveniles are preyed upon by the Smallmouth Bass, Micropterus dolomieu, the Largemouth Bass, Micropterus salmoides, the White Bass, Morone chrysops, and various birds. Reproduction is oviparous with each female placing between 2,000 and 6,000 eggs in small holes or depressions on the lake floor which are then fertilized and guarded by males. Eggs hatch within a week and pups are guarded by both parents for a short time. They are known to “hibernate” by burying themselves in the substrate during low oxygen and low temperature episodes. They have a lifespan of up to 10 years.
In Mexican waters the Black Bullheads have a very limited documented range being native only to the freshwater systems of northern Mexico.
The Black Bullhead is not easily confused with any other species as it is unique among catfish for having a black barbel, a tan crescent around the tail, and a square caudal fin. However, it is often confused with the Brown Bullhead, Ameiurus nebulosus (strongly serrated pectoral spines; 21 to 24 anal rays) which is not presently documented in Mexican waters.
The Black Bullheads are not actively pursued by recreational anglers but are caught occasionally as a by-catch. They are considered an excellent food fish being raised at a modest level via aquaculture. They have been widely introduced to all parts of North America, Europe, and South America for sport and food where they have very quickly become highly invasive, a nuisance, and unpopular in most locations. Efforts to eradicate local populations have faced major challenges and it appears that entire water systems would need to be poisoned to completely remove established populations of Black Bullheads. They have been credited with eradicating local populations of the endangered Humpback Chub, Gila cypha and the Leopard Frog, Rana chiricahuensis, removing food sources for native fish, and increasing turbidity in water systems. They have been used on a limited basis by the aquarium trade but are known to consume fellow tank mates. From a conservation perspective they are currently considered of Least Concern with wide global distribution, increasing population trends, and adult global populations estimated to be in excess of one million individuals.
Black Bullhead, Ameiurus melas. Fish caught from a tributary of the Upper Niagara River, Ontario, Canada, June 2014, Length: 23.0 cm (9.0 inches). Catch, photo, and identification courtesy of Kenneth Tse, Toronto, Canada.