EARLY DEVELOPMENT OF THE AUSTRALIAN CRIMSON-SPOTTED RAINBOWFISH, MELANOTAENIA-FLUVIATILIS (PISCES, MELANOTAENIIDAE)

This paper describes the early ontogeny of the crimson-spotted rainbow fish Melanotaenia fluviatilis. Eggs ranged in size from 0.98 to 1.07 m m and 35-45 oil droplets were present, as were numerous adhesive filam ents which originated from one point. Hatching was predominantly 7-9 d ays after spawning at 25.5 degrees C. At hatching, larvae (4.2 mm stan dard length) had a reduced but still present yolk sac and were strong enough swimmers to remain in the upper 1 cm water layer. The swim blad der inflated within 10 h of hatching and the first ingested food was o bserved after 12 h. At 32 days after hatching, the mean larval length was 13.86 mm and at 72 days was 21 mm. Knowledge of the critical devel opmental stages described in the paper is important in understanding t he impact of the major biotic modifying factors influencing the impact of chemicals and other pollutants on rainbowfish, especially given th at they are used by ecotoxicologists as a surrogate species for Austra lian freshwater fish in general.