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• Biology and early development of eight fish species from the Alligator Rivers Region (PDF 1,182 KB)

About the report

The following fish were studied: Melanotaenia nigrans, Melanotaenia splendida australis, Melanotaenia splendida inornata, Pseudomugil gertrudae, Pseudomugil tenellus, Craterocephalus nov. sp., Craterocephalus stercusmuscarum stercusmuscarum, and Ambassis macleayi.

Coloration, other specific attributes, sexual dichromatism and dimorphism were recorded whenever possible so that the sexes could be easily recognised. Mating and other behaviour patterns were noted to facilitate recognition of breeding pairs. Spawning patterns and occurrence of cannibalism were recorded, as was the effect of the presence of more than one breeding pair in a tank.

Egg numbers at each spawning were recorded and the main breeding season for each of the species was determined. No single stimulus to spawning could be determined. Spawning appeared to be sporadic but continuous throughout the year, with a peak during late spring/early summer.

Detailed records of embryonic development were kept for all species except Ambassis macleayi. Descriptions and drawings of stages were made and where possible, distinguishing features noted so that the embryos of different species could be recognised. Time of development to hatching, at constant temperature, was recorded.

Larval development of rainbow-fishes was recorded in detail and times to particular developmental stages noted and compared. For other species, the times to particular developmental stages were recorded and representative larval stages described and drawn.

General recommendations are made in regard to the requirements to breed and maintain fish, the numbers that can be produced for further study and the constraints that may be present when working with selected fish.