Breeding biology, and egg and larval development of Galaxias rostratus Klunzinger, the Murray Jollytail from inland New South Wales

Abstract

G. rostratus the Murray Jollytail bred in earthen ponds at the Inland Fisheries Research Station, Narrandera, NSW, when surface and bottom water temperatures were above 10.5°C during August and September. Flooding was unnecessary but there was water flow through the pond. Eggs were demersal, transparent, spherical, telolecithal and slightly adhesive; possessed a cluster of oil globules; varied from 1.35mm to 1.66mm in diameter; and appeared to be scattered randomly on the pond bottom during spawning. Eggs hatched after 81/2 to 91/2 days. The length of recently-hatched larvae ranged from 5.7mm to 8.1mm. The pro-larval stage terminated at around 5days after hatching. Water temperatures varied between 13.8 and 20.0°C during development. The largest adults collected were 15.0cm and weighed 22.5gm. Marked colour differences between the sexes were not obvious, but sex could be determined by the appearance of gonads through the transparent window anterior to the vent close to the breeding season. Fecundity of the females varied from 2300 eggs at 86mm body length and 4.7gm body weight to 7000 eggs at 136mm length and 19gm weight. The gonosomatic index rose to 40.0 and 31.2 in females and males respectively prior to breeding. The breeding and larvae of G. rostratus are compared to other Australian mainland Galaxiidae, and other freshwater fish larvae of inland NSW.