Catfish (Ameiurus nebulosus)
Species: A. nebulosus
Binomial name: Ameiurus nebulosus
Synonyms: Ictalurus nebulosus, Pimelodus nebulosus
Common name: Catfish, Brown bullhead, Mud pout, Horned pout, Mud cat
Ameiurus nebulosus is the only member of the Ictaluridae family that occurs in New Zealand waters. This catfish were introduced into New Zealand from America in the 1870s, the reason is unknown. For many years, they were rarely encountered with the only known populations occurring in the lower Waikato River and in Lake Mahinapua south of Hokitika in the South Island. They were first recorded from Lake Taupo in 1985. Since then, catfish have gradually spread throughout Lake Taupo and down the Waikato River. In 1997, catfish were recorded for the first time from the Kaituna Lagoon near Lake Ellesmere, and in 2003 from a stream entering Hokianga Harbour, Northland. Accidental introductions via boat trailers and especially fyke nets used for eeling are continuing to spread this species around New Zealand.
Catfish are robust fish with distinctive whisker-like barbels (feelers). They have sharp spines at the front of the pectoral and pelvic fin. In New Zealand they often grow to 30 cm and 2 kg. They can survive in a wide range of temperatures and tolerate poor water quality. They are able to survive for long periods out of water and are difficult to kill. They are carnivorous and use their sensitive barbels to probe the substrate and locate insects, crustaceans, molluscs and small native fish. New Zealand’s freshwater crayfish are a major prey species.
Nests are built by one or both sexes. After a period of caressing each other with their barbels, male and female settle over the nest, face opposite directions (while maintaining body contact) and spawn. Although eggs are cared for by one or both parents, there have been reports of parents eating their own eggs. Caring entails fanning by the paired fins, moving and stirring by the barbels, and may be picked up and ejected from the mouth; this ensures hatching.
In New Zealand all catfish must be killed on capture and not returned to the water alive.
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