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Freshwater Catfish, Eel-tailed Catfish, Dewfish, Kenaru, Tandan
Conservation status: Least Concern
The scientific name Tandanus tandanus for the Freshwater Catfish comes from an aboriginal name for the fish - "Tandan" - which Major Thomas Livingston Mitchell recorded on his 1832 expedition.
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Scientific Classification
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Actinopterygii
Siluriformes
Plotosidae
Tandanus
tandanus
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| Freshwater Catfish can grow up to a length of 90 cm and weigh up to 7 kg, but fish over 45 cm and 2 kg in weight are considered exceptional. The fish have have a large head with small eyes, thick and fleshy lips and tubular nostrils. The down-turned mouth is surrounded by four pairs of barbels (whiskers). They have a long, almost cylindrical body that tapers into a pointed, eel-like tail. A continuous fin surrounds the tail. The first dorsal and pectoral fins have sharp spines that can cause a nasty wound. The spines are also venomous and this poison can make an adult human very sick. Freshwater Catfish don't have scales, instead their body is covered with a smooth, slimy skin. Colour is variable - grey, brown, olive-green, reddish or even purplish on top with a pale belly. They are usually mottled with dark brown to black blotches.
The species usually inhabits deep, slow-flowing streams and lakes and can be found in the Murray-Darling River systems and other coastal drainages from northern Queensland, into New South Wales and Victoria. Although once widespread, populations have declined significantly since the 1980s - most likely because of the introduction of carp, thermal pollution and silt build up.
Freshwater Catfish are mostly bottom feeders. They eat crustaceans, mollusks, small fish, aquatic insects and the larvae of dragonflies, caddisflies and mayflies.
Spawning season is in Spring and Summer. One or two weeks before spawning, a male catfish will build a circular nest out of gravel and pebbles. This nest can be up to two metres across and it has a central depression where the female lays her eggs. The eggs are fairly large (3 mm), spherical and aren't adhesive. Instead of sticking to plants or rocks, the eggs sink and get trapped between the pebbles and gravel in the bottom of the nest. Either one or both parents stay with the eggs to guard them until they hatch. This takes from two to seven days. Freshwater Catfish become sexually mature at three to five years of age. They are known to spawn multiple times during a season.
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