The Effect of Stocking and Feeding Rates on Growth and Production of Feeder Goldfish in Pools

Abstract

Millions of small goldfish Carassius auratus are sold each year as “feeders” to pet stores and zoos around the nation. This specialty market requires specific size ranges of fish to be available year-round. Feeder goldfish producers normally must stunt fish growth through a combination of high stocking and low feeding rates to satisfy market conditions. Production information on growth at varying stocking and feeding rates is essential to evaluate whether increasing stocking density alone could slow or stop fish growth. Three 126-d trials were conducted in continually aerated 5.9-m² plastic-lined pools. In trial 1, juvenile goldfish (0.21 g) were cultured at 84, 168, or 252 fish/m² and fed a commercial feed containing 36% crude protein at a rate of 3% body weight/d. Trial 2 compared the growth of goldfish (0.68 g) stocked at 254/m² and fed at rates of 1, 2, or 3% body weight/d. The third trial examined the growth of goldfish (0.69 g) stocked at 254, 508, or 763 fish/m² and fed at a rate of 1% body weight/d. The results of trial 1 showed that while fish growth was slower at higher stocking densities, fish in all treatments grew rapidly through the target size range (1.1–1.8 g). Only by feeding at a rate of 1% body weight/d could fish be kept within market size for the 126-d period (trial 2). This held true for all three stocking rates tested in trial 3, although survival was reduced at the highest density. At a stocking rate of 254/m² (trial 2), fish condition (K) was not different (P > 0.05) among the 1, 2, and 3% body weight/d feeding rate treatments, indicating that restricted feeding alone did not necessarily result in significantly poorer fish condition.