Spawning, development and distribution of the southern pigmy perch Nannoperca australis australis Gunther from inland waters in eastern Australia

Abstract

Southern pigmy perch were bred in ponds on three occasions when water temperatures rose above 21.0�C at the surface and 19.3�C at the bottom during the months of September and October. Flooding was found not to be necessary as a breeding stimulus. The requirements for breeding and the embryological development of eggs and larvae were followed closely. The eggs were demersal, transparent, spherical, telolecithal and essentially non-adhesive; possessed a cluster of oil globules; varied from 1.16 mm to 1.35 mm in diameter; and were scattered randomly during spawning. They hatched after between 2 days 18 hr and 3 days 7 hr at temperatures fluctuating between 15.8�C and 25.3�C. The length of the recently hatched larvae varied between 3.18 and 3.92 mm. The pro-larval stage terminated at 5 days 23 hr at temperatures between 15.8 and 23.7�C. The largest adult recorded at Narrandera was 63 mm in length and weighed 3.48 g. Marked colour difference occurred between the sexes as the breeding season approached, the males possessing bright red fins with black edges. Fecundity of the females varied from 506 eggs at 40 mm length and 0.86 g weight to 4217 eggs at 63 mm length and 3.49 g weight. The gonosomatic index rose to 11.4 and 4.7 in females and males respectively prior to breeding. Fish 6 months, 18 months and 30 months old from a pond reached 3.0, 3.8 and 4.7 cm respectively. Some taxonomic problems of the Nannopercidae are discussed and the distributions of the different forms given. The breeding of .Edelia vittata and Nannoperca australis australis are compared.