Controlled Spawning of Laboratory Reared Fathead Minnows (Pimephales promelas) and Effect of Different Diets on Survival and Growth of the Fry

Abstract

Fathead minnows (Pimephales promelas) were maintained through 2 generations under controlled environmental conditions (20-25°C; 16 h light: 8 h dark) in the Wet Laboratory at SUNY-Brockport. Fish were cultured in reuse systems; 2 units for adult fish (segregated by sex), 1-2 units for subadult fish and juveniles, and 1-2 units for breeding fish. Each unit consisted of a 244x61x30 em trough and a 0.07lt- m3 biological filter composed of 2.5-7.6 cm gravel and crushed oyster shells. Water flowed by gravity from the trough to the biofilter and was returned to the trough by a submersible pump, at a rate of 42-114 L/min. The reuse systems required less maintenance (5-10min/day/unit) and promoted better survival and growth than the 30 L static units also used to maintain fathead minnows. Consistent reproduction was usually obtained within 7 days after 4 males and 8 females were introduced to a breeding unit. Intracoelomic hormonal injection, with 10 IU Human Chorionic Gonadotropin, promoted earlier spawning and increased egg deposition. Feeding studies using 3 different prepared feeds, Artemia, and controls (no food) were run with < 24 h old fry and terminated after 30 days. Best survival (>86%) and growth were obtained with Artemia; survival with prepared feeds was poor (< 20%). There was no apparent benefit from combining Artemia and prepared feeds.