 |
|||
| Common Name | |||
| Freshwater catfish (Jewfish, Eeltail catfish) | |||
| Scientific Name | |||
| Tandanus tandanus Mitchell, 1838 | |||
| Conservations Status | |||
| Declining | |||
| Distribution and Abundance | |||
 |
|||
| This catfish is widespread throughout the Murray-Darling Basin, but generally in the lower, slow-flowing rivers. It (and a number of suspected cryptic species) is also found in coastal rivers from southern NSW to northern Qld. It has been stocked into some farm dams and lakes where it can establish breeding populations. Most riverine populations have declined significantly since the late 1970s/early 1980s, and the species is no longer common in many areas where it was formerly abundant. Some populations in impoundments seem to be faring better. The species was relatively abundant in the Qld portion of the Basin until recently. It is still common in the upper Condamine River but has disappeared from the Paroo and is now in relatively low numbers in the lower Condamine and Warrego rivers. | |||
| Identification | |||
| A medium sized species with a laterally compressed rear portion of the body. Maximum length 900 mm and maximum size 6.8 kg; usually < 500 mm and < 2 kg. The head is large and four pairs of barbels surround the large mouth, with its thick fleshy lips. The first dorsal fin is short but high, just behind the head, and has a stout, serrated spine at the front of the fin. The second dorsal fin is continuous with the caudal and anal fins, hence the species' alternative common name of Eel-tailed catfish. The skin is smooth, with no scales. The back of adults is usually olive-green to brown, and the belly whitish. Juveniles tend to be grey-brown, mottled with darker blotches. | |||
| Biology and Habitat | |||
| Freshwater catfish is a benthic species that prefer slow-flowing streams and lake habitats. Individuals are sexually mature at 3-5 years of age and spawn in spring and summer when water temperatures are 20-24¡C. The nest is a circular to oval depression, 0.6-2.0 m in diameter, constructed from pebbles and gravel, with coarser material in the centre. The eggs are large (~3 mm), non-adhesive, settle into the interstices of the coarse substrate, and take up to seven days to hatch. The male fish remains with the nest to fan, clean and guard the eggs. It has been suggested that there may be multiple spawnings in a single nest in a season, either sequentially or concurrently. Larvae are about 7 mm long at hatching. The Freshwater catfish is a relatively sedentary species and adults show very limited movement compared to cod and perch; most individuals move less than 5 km. This catfish is predominantly an opportunistic carnivore and the adult diet consists mainly of shrimps, freshwater prawns and yabbies, with aquatic insects, snails and small fishes also important. Aquatic insects are more important in the diet of juvenile fish. Adults are mostly active at dusk and in the early evening. |
|||
| Potential Threats | |||
| Numerous threats have contributed to the decline in this species. Concern has been expressed about the potential impacts of Carp and Redfin perch on riverine populations. Cold-water pollution below dams, barriers to movement, changes to natural flow regimes and elevated salinity levels (juveniles have much lower salinity tolerance than adults), are also suspected as causes of declining local populations. The lack of formal recognition as a threatened species has hampered conservation efforts | |||
| General References | |||
| Click here for complete list of references | |||
Clunie & Koehn 2001a,b; |
|||
Davis 1977a,b,c; |
|||
Pollard et al . 1996; |
|||
Pusey et al . 2004; |
|||
| Morris et al . 2001; | |||
| Reynolds 1983. | |||
| PDF Links | |||
| To download these PDFs visit our on-line publications ordering system through these links. | |||
| Fish Factsheet - Freshwater catfish | |||
| Fishes of the Murray-Darling Basin: An introductory Guide | |||