Growth and survival of Rhamdia
quelen (Siluriformes, Pimelodidae) larvae exposed to different levels of
water hardness
C. R. Townsend, L. V. F. Silva, B. Baldisserotto-2003
Aquaculture, 215(1-4): 103-108
Abstract:
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-l 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.
(Departamento de Fisiologia, Universidade Federal de
Santa Maria, 97105.900, Santa Maria, RS, Brazil, Tel.: +55-55-220-8342; fax:
+55-55-2208241; email of B. Baldisserotto: bernardo@ccs.ufsm.br;
bbaldisserotto@hotmail.com)