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Eel-tailed catfish
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Siluriformes Family: Plotosidae Genus: Tandanus Species: T. tandanus
Binomial name
Tandanus tandanus (Mitchell, 1838)

Contents 1 Range 2 Size, appearance and diet 3 Reproduction 4 Conservation 5 External links 6 References

The eel-tailed catfish, Tandanus tandanus, is a freshwater fish native to the Murray-Darling river system of Australia. The scientific name for eel-tailed catfish comes from an aboriginal name for the fish - Tandan - which Major Mitchell recorded on his 1832 expedition.

It was originally found in most freshwater habitats of the Murray-Darling river system except for the upland, sub-alpine and alpine headwaters of southern tributaries. It is also present in speciated but undescribed forms in several east coast systems in northern New South Wales due to natural river capture events.

Eel-tailed catfish are commonly 1 to 2 kg in weight but occasional exceptional specimens of 6 to 7 kg have been recorded.

Eel-tailed catfish have a downturned mouth with fleshy lips surrounded by a number of "whiskers" which assist them with feeding. They are a solid, almost cylindrical, elongate fish, with the posterior half of their body tapering into a pointed eel-like tail. A continuous fin margin surrounds this tapering posterior half of the body. Their eyes are small. Colouration is variable but most commonly a mottled greyish-purple colour.

Eel-tailed catfish are generalised carnivores, foraging on the bottom of lake and stream beds at moderate depths for shrimps, yabbies and other prey.

Eel-tailed catfish spawn in spring, and are cued by increasing photoperiod (daylight length) and increasing water temperatures. They build large nests up to a metre in diameter with small stones and gravel, within which the eggs are laid. Males guard the eggs until they hatch.

The Murray-Darling species of eel-tailed catfish has declined significantly over recent decades, and concern is growing. Most populations in the southern half of the Murray-Darling river system are extinct or nearly so.

There are suggestions that introduced carp, with similar mouth structures and feeding habitats, compete severely with eel-tailed catfish, to the detriment of the catfish.

Severe siltation also probably severely impacts upon the species spawning by smothering the rocks and pebbles they use to build nests.

Fortunately, populations in several rivers and impoundments in the northern half of the Murray-Darling appear secure for now. Interestingly, the species does well in the upland reaches of these northern Murray-Darling rivers; this is in contrast to its absence from the upland reaches of southern Murray-Darling rivers, where water temperatures are cooler.

• Native Fish Australia - Eel-tailed catfish page

• Tandanus tandanus (TSN 640215). Integrated Taxonomic Information System. Accessed on 11 March 2006.
• "Tandanus tandanus". FishBase. Ed. Ranier Froese and Daniel Pauly. August 2005 version. N.p.: FishBase, 2005.