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identificationA 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 habitatFreshwater 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.

Common name Freshwater catfish (Jewfish, eeltail catfish) Declining

scientific name Tandanus tandanus Mitchell, 1838

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F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 57An introductory guide56 F i s h e s o F t h e M u r r ay- Da r l i n g B a s i n 57An introductory guide56 An introductory guide 57

Distribution and abundanceThis 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.

Potential threatsNumerous 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 referencesClunie & Koehn 2001a,b; Davis 1977a,b,c; Pollard et al. 1996; Pusey et al. 2004; Morris et al. 2001; Reynolds 1983.

iD VALLey 1 Avoca 2 Border rivers 3 Broken 4 campaspe 5 castlereagh 6 central Murray 7 condamine 8 darling 9 goulburn 10 gwydir 11 Kiewa 12 Lachlan 13 Loddon 14 Lower Murray 15 Macquarie 16 Mitta Mitta 17 Murrumbidgee 18 namoi 19 ovens 20 Paroo 21 upper Murray 22 Warrego 23 Wimmera

Published by the Murray-Darling Basin Commission Postal address: GPO Box 409, Canberra ACT 2601 Office location: Level 3, 51 Allara Street, Canberra City ACT Telephone: (02) 6279 0100, international + 61 2 6279 0100 Facsimile: (02) 6248 8053, international + 61 2 6248 8053 Email: info@mdbc.gov.au Internet: http://www.mdbc.gov.au

For further information contact the Murray-Darling Basin Commission office on (02) 6279 0100

This fish fact sheet is an extract derived from the report: Lintermans, M. 2007, Fishes of the Murray-Darling Basin: An introductory guide.

MDBC Publication No. 10/07

ISBN 1 921257 20 2

© Murray-Darling Basin Commission 2007

This work is copyright. Graphical and textual information in the work (with the exception of photographs, artwork and the MDBC logo) may be stored, retrieved and reproduced in whole or in part provided the information is not sold or used for commercial benefit and its source (Fishes of the Murray-Darling Basin) is acknowledged. Such reproduction includes fair dealing for the purpose of private study, research, criticism or review as permitted under the Copyright Act 1968. Reproduction for other purposes is prohibited without the permission of the Murray-Darling Basin Commission or the individual photographers and artists with whom copyright applies.

To extent permitted by law, the copyright holders (including its employees and consultants) exclude all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this report (in part or whole) and any information or material contained in it.

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