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Strongylura krefftii (Family Belonidae)

Freshwater Longtom

Distribution:

The Freshwater Longtom is occasionally caught in southern Queensland but they mostly occur northwards of the Kolan River (near Bundaberg) throughout Queensland and west as far as Western Australia. They are also present in New Guinea (QLD, NT, WA).

Features:

Freshwater Longtom are known to reach 900 mm but are commonly about half this size. Freshwater Longtom are long slender fish with elongated jaws and lots of long needle-like teeth. They have very small scales and the dorsal and anal fins are located toward the rear of the body near the caudal fin. The eyes are large, dark blue and have a yellow ring. Their colouration depends on the environment. In estuaries and marine waters they are silvery, in freshwaters the body is markedly counter shaded. The back is dark olive green that becomes slightly lighter on the lateral line. Below the lateral line, the sides are silvery and the belly is white. Each scale has a greyish iridescent speckling. Larger fish may have dark markings on the upper sides that may give the impression of three lines along the body. The lateral line often is highlighted.

Ecology/Way of Life:

Freshwater Longtom are common in estuaries and the lower reaches of rivers. They are rarely found in the upper reaches of rivers. They have also been introduced to some impoundments where they form self-sustaining populations. They are usually seen close to the surface either signally or in small schools (packs). In impoundments, (Callide Dam) the breeding season may extend from spring to autumn. Running ripe fish have been collected in October, November and April at water temperatures between 23 and 26°C. Unfertilised eggs are a translucent golden colour and are about 8.0 to 10.0 mm in diameter. A female 780 mm long contained several thousand eggs. Freshwater Longtom are carnivorous and often ambush prey amongst waterlilies. The diet is primarily smaller fishes, but insects are also taken. Growth rates are unknown. A group of fish 500 to 550 mm long weighed 419 to 542 g and fish between 700 to 800 mm long weighed between 1290 to 2258 g.

Interaction with Humans/Threats:

Freshwater Longtom provide exciting sport for recreational anglers. They take surface lures and will jump clear of the surface when hooked. In fact they can tail-walk for quite a distance. They can be hard to hook well because of the bony elongated mouth. They are good eating and the flesh is clean and white. Experienced aquarists occasionally keep juveniles, although they are quite aggressive to any other tank inhabitant. They require live foods and a long aquarium with a strong cover, as they will jump.

Other Comments:

Strongylura krefftii was named by Gunther in 1866.

Further Reading:

Allen, G. R., Midgley, S. H. & Allen, M. (2002). Field Guide to the Freshwater Fishes of Australia. Western Australian Museum. Perth. 394pp.

Leggett, R. & Merrick, J. R. (1987). Australian Native Fishes for Aquariums. J. R. Merrick Publications. Sydney. 245pp.

Merrick, J. R. & Schmida, G. E. (1984). Australian Freshwater Fishes: Biology and Management. Griffith Press Ltd. 409pp.

Acknowledgments:

Text: Rob Wager & Peter J. Unmack. Distribution map: Peter J. Unmack. Photographer: Gunther Schmida.

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