Salinity Adaptability and Tolerance of Hatchery Reared Comet Goldfish Carassius auratus (Linnaeus 1758)

A study was carried out in the laboratory on adaptability and tolerance of hatchery reared Comet goldfish, Carassius auratus (Linnaeus 1758) to varied salinity regimes, to provide baseline data and information on possibility of its culture in brackish water or marine environment. A total of two hundred and twenty life juvenile of goldfish, aged eight months used in this study were raised in and purchased from a reputable fish farm in Lagos, Nigeria. Biometric data on total length (T) and body weight (BW) measurements were recorded in the fisheries laboratory of Lagos State University. Goldfish of 17 to 25 cm total length, weighing between 70 and 145 g body weight were subjected to 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 parts per thousand () salinities in the laboratory. There was a significant decrease in total length and body weight measurements with increased salinity. Mean growth rate (MGR) of 39.196, 34.783, 34.555, 20.889, 15.852 and 10.645 g day-1 were observed in 0, 1, 2, 3, 4 and 5 , respectively, while the specific growth rates (SGR) were 0.012, 0.011, 0.008, 0.008, 0.005 and 0.005 g day-1, respectively. No death (0% mortality) was recorded in 0, 1, 2 and 3 . The most adaptable salinity was 0 ; the fish however exhibited high level of tolerance between 1 and 5 salinities. The baseline data from this study indicate that gold fish, Carassius auratus will adapt and tolerate culture systems of fresh and low brackish water environments of 0 to 5 salinities.