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Brown bullhead catfish are a dark brown to olive green colour with paler sides and bellies. They have eight distinctive barbels around the mouth, small eyes and smooth, scaleless skin. The leading edge on their dorsal and pectoral fins has a sharp toxic spine. Catfish are an extremely robust fish and can survive for very long periods out of water. They commonly grow to 250-500mm long, and live for 5-8 years. They are opportunistic generalist feeders. Juveniles predominantly eat zooplankton and invertebrates. The adult diet broadens to include a wider range of macroinvertebrates as well as molluscs, vegetation and fish. Catfish are predominantly nocturnal, but there is some diurnal activity as well.
Lakes and slow-moving water bodies including streams and drainage channels. They favour areas with submerged vegetation. Spatial use of habitats within an invaded water body can vary seasonally to meet changing spawning and/or food requirements. They have broad environmental tolerances including very low dissolved oxygen levels.
Tolerance of poor water quality enables them to cope with habitats that many other species are unable to tolerate. Tolerance of low oxygen levels may also increase risk of surviving human-mediated dispersal between water bodies. Invasive overseas.
Catfish form pair-bonds are are territorial during the preparation of the spawning site and during spawning. They usually spawn between September and December. Spawning occurs in shallow depressions in bottom mud or sand. In New Zealand catfish mature at two years old and are able to spawn for the next 4-5 years. They are one of the few freshwater fish species that provide parental care of their broods, significantly increasing offspring survival.