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Freshwater Catfish Tandanus tandanus

Freshwater Catfish Tandanus tandanus


Tandanus catfish is an eel-tailed catfish, the body is stout (dark) and posteriorly compressed. Head large and flattened below, with eyes of moderate size. The down-turned mouth has thick fleshy lips with tubular nostrils in front border of upper lip, pointing forward. There are four pairs of barbels around the mouth. First dorsal fin is short based, high on back just behind the head and preceded by a strong serrated spine. Second dorsal fin originates just behind origin of anal fin and is continuous with tail and anal fin. Pectoral fins located low on body, also have strong serrated spines. Skin is smooth and tough with no scales.

Sexual Dimorphism (differences)

At around 1 year of age, the sexes can be distinguished by shape of urinogenital papilla, which is triangular in females and cylindrical in males.


When less than 150mm long, freshwater catfish are grey or brown dorsally and laterally usually mottled with dark brown to black blotches, fading to whitish below. This mottling usually disappears in large fish which vary form olive green to brown, reddish brown or even purplish in colour above , fading to whitish below.

Size range from up to 900mm and 7kg. However, fish over 2kg are not common.


Distribution Freshwater CatfishDistribution Freshwater Catfish

Tandanus catfish are widespread thoughout the Murray-Darling system in inland Queensland, New South Wales, Victoria and South Australiabut not upstream of Wagga Wagga in the Mrurrumbidgee River or Mulwala in the Murray River, probably owning to cool water discharges from large dam; also present in many coastal rivers of eastern Australia from around Sydney to north Cairns.

Life Cycle

Tandanus spawn when temperatures rise during spring and summer. Spawning is not stimulated by flooding. The number of eggs increases with size, ranging from about 2800 to 20,600 eggs in females between 390 and 530mm lon. They build a circular to oval nest, generally around 0.6-2m in diameter, from pebbles and gravel.

during courtship, both male and female circle and weave above the nest. The female then arches her body, agitates her pelvic fins and releases the eggs about 30cm above nest. They are spherical, non-adhesive and a light greenish yellow in colour. Males fertilises eggs, which sinks to the bottom, settling in gravel of nest. One of the adults, usually the male, remains at nest until the eggs hatch in about 7 days. The larvae are about 7mm long when they hatch, and barbels appear on the young after about 3days. They grow quickly reaching 90mm by their first winter and 500mm in their sixth.

Young catfish feed on Zooplankton and small insects especially chironomid midge larvae. Catfish longer than 100mm also eat small fish such as western carp, gudgeon, blue eyes, rainbows.

Tandanus Catfish in ponds and Dams

Catfish are only suited for large ponds and dams. In aquariums they need to be by themselves or with larger species of fish. In ponds, Tandanus need to be with larger fish and not with ‘frog friendly’ fish. This is because they eat small fish due to the fact that they are highly predatory nature. If the pond is bigger though (20000 litres and above), they can be introduced with smaller species because of the large space. Same thing applies for Dams, due to the large space, they can be introduced as a way of balancing the ecosystem.