whiskered bottom feeder, slow and hardy

Size
Length: 20–40 cm, Weight: 0.5–2 kg
Lifespan
8–12 years
Diet
Insects, crustaceans, fish eggs and plant matter. Lives in warm, slow, murky waterways: lakes, ponds and sluggish lowland rivers. A bottom-dwelling scavenger, hiding under logs and in deep holes during the day.
Habitat
Warm, slow, murky waterways: lakes, ponds and the sluggish reaches of lowland rivers. The fish of the dark water, hiding under logs and in deep holes during the day.
Range
North Island, particularly in Lake Taupō and other lowland lakes. Most common in warm, slow, murky waterways with soft, muddy bottoms. Introduced from North America, now considered a major pest.
Endemism
Introduced
Main Threats
None. This introduced species is considered a major pest. Controlled by the Department of Conservation in some areas, particularly in Lake Taupō where they threaten trout fisheries.
Population
Introduced and considered a pest. Established populations in several North Island lakes, including Lake Taupō. A major threat to native fish and trout, competing for food and preying on eggs.
Conservation Status
Introduced
The ugly invader of the muddy bottom. This fish should never have been brought here. It has a thick heavy body, a large flattened head and a wide whiskery mouth. Eight barbels surround the mouth. These are the catfish whiskers. The skin is smooth and scaleless. It ranges from olive-brown to almost black on the back. It fades to a pale yellowish belly. The dorsal and pectoral fins are armed with sharp venomous spines. They can cause a painful sting. A fish that fights back. The defence is chemical. The warning is physical. Nocturnal vacuum cleaners define the species. During the day, brown bullhead catfish hide under logs. They rest in rock piles or in deep holes. They do nothing. At night they emerge and start eating. Not picky. Insects, worms, snails, small fish, fish eggs, crayfish, even dead things. They will eat anything that fits in their mouth. Their mouth is surprisingly large. A fish that eats without discrimination. The appetite is indiscriminate. The capacity is high. A nightmare for lake managers. Catfish breed like crazy. They eat everything in sight. They are incredibly hard to remove once they establish. Tough survivors. They can survive out of water for hours. They tolerate low oxygen water. They endure freezing conditions. A fish that refuses to die. The resilience is absolute. The persistence is problematic. The removal is difficult. To catch a catfish is to catch a problem. The fish that should not be here. It does damage that cannot be undone. No Māori name because it is not a native fish. It came from North America. Probably released from an aquarium or a farm pond. Today it is the fish of the dark hole. The one caught when fishing for trout. Wondering why the bait is not working. Only to pull up a whiskery, slimy, stinging pest. The disappointment is real. The catch is unwanted. The lake is murky. The catfish hides under a log, waiting for night. The angler casts for trout. The catfish takes the bait. The angler swears. The frustration is immediate. The outcome is predictable. The ecosystem suffers. The catfish does not care. It just eats. That is what it does. The intent is simple. The impact is complex. The existence is intrusive. No one told it otherwise.