Hormone-inducedovulation, naturals pawningand larviculture of Brazilian flounder Paralichthys orbignyanus (Valenciennes, 1839)

Abstract

Mature Brazilian £ounders Paralichthys orbignyanus were captured in coastal southern Brazil and their reproduction in captivity was studied. Brazilian £ounder will spawn naturally in captivity when the water temperature is around 231Cand14hoflightis provided daily. Females were induced for ovulation and hand stripping using human chorionic gonadotropin, luteinizing hormone-releasing hormone analogue or carp pituitary extract. There was no need to inject males, as running milt was observed during the spawning season. Fertilization and hatching rates were above 80% independent of the hormone used. Notochord length at hatching was 2.18  0.07 mm for larvae hatching from naturally spawned eggs. Larvae were reared in salt water (30^35 g L  1)at 241C and under continuous illumination. Larviculture was with green water (Tetraselmis tetrathele 50  10 4 cells mL  1). Rotifers (10^20 ind mL  1) were o¡ered as ¢rst food 3 days after hatching and gradually replaced by Artemia nauplii (0.5^ 10 i n d m L  1). Larvae settled to the bottom 20 days after hatching and completed metamorphosis within a week after that. The total length for newly metamorphosed juveniles was 12.9  2.2 mm and the mean survival was 44.8%. The results demonstrate the feasibility of producing Brazilian £ounder ¢ngerlings for stock enhancement or grow-out purposes.