Growth and survival of Rhamdia quelen (Siluriformes, Pimelodidae) larvae exposed to different levels of water hardness

摘要

The response to water hardness increase varies from species to species. The purpose of this study was to verify the survival and growth of larvae of silver catfish, Rhamdia quelen, in water with different levels of water hardness. Larvae (2.75 mg and 5.00 +/- 0.05 mm) were randomly allotted to experimental units (three replicates per treatment) and kept in 44-1 boxes (400 larvae/box). Larvae were exposed to five water hardness values (30, 70, 150, 300, and 600 mg l(-1) CaCO3) at pH 8.25. Samples of larvae were collected on days 0, 7, 14, and 21, and the length, weight, and specific growth rate (SGR) were determined for each collection. Survival and biomass were calculated on day 21. Higher larvae growth, survival, and biomass were obtained at 30 and 70 mg l(-1) CaCO3. Therefore, this is the recommended hardness range for growth and survival of silver catfish larvae.