The effects of acute and chronic exposure to water salinity on juveniles of the carnivorous freshwater catfish Lophiosilurus alexandri

• Published in: Aquaculture Vol. 481; pp. 255 - 266
• Main Authors: Mattioli, Cristiano Campos, Takata, Rodrigo, Paes Leme, Fabíola de Oliveira, Costa, Deliane Cristina, Melillo Filho, Reinaldo, de Souza e Silva, Walisson, Luz, Ronald Kennedy
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2017
• Subjects: Blood biochemistry; Hematology; Stress; Hematology; Blood biochemistry; Performance; Stress
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2017.08.016

This work aims to evaluate the tolerance, growth, metabolism, hematology and blood biochemistry of juvenile Lophiosilurs alexandri exposed to different water salinities. In Experiment 1, juveniles (28.6±1.3g weight and 12.8±1.8cm length) were transferred directly from freshwater to water with salinities of 0 (freshwater), 2.5, 5.0, 7.5, 10.0, 12.5 and 15.0g of salt/L, and observed for 96h. In Experiment 2, juveniles (15.5±0.8g weight and 11.0±1.0cm length) were subjected to saline treatments of 0 (freshwater), 2.5, 5.0, 7.5 and 10.0g of salt/L for 28days with, juveniles being acclimated gradually every 6h, to reach the desired salinity levels in 24h. In Experiment 1, at 24h of osmotic shock, the CL50-24h was estimated to be 11.6g of salt/L. At the end of 96h, the survival rate was 100% up to salinity 7.5g of salt/L, while at 10.0g of salt/L it was 58.3%. Total mortality occurred with 12.5 and 15g of salt/L. At 24h, changes in glucose, hemoglobin, osmolarity, hematocrit, cortisol, alanine aminotransferase and chloride ions were recorded. However, there were no significant differences in total plasmatic protein, triglycerides, cholesterol and albumin (p>0.05). In Experiment 2, there was total mortality on the 21st day of the experiment with 10g of salt/L. At 28days, the survival rate was 100% between freshwater and 5g of salt/L. In terms of biomass gain and feed conversion, a quadratic response with higher estimated levels at 2.01 and 2.45g of salt/L were recorded, respectively. Weight gain, daily weight gain and specific growth rate were constant until the estimated values of 2.64, 2.63 and 2.83g of salt/L, respectively, then decreasing in higher salinities. For whole fish composition, phosphorus and protein exhibited a quadratic response with the highest level estimated at 3.24g of salt/L and the lowest estimated level at 0.98g of salt/L, respectively. Constant values for energy were recorded until the estimated salinity at 2.15g of salt/L. Comparing the hematological and biochemical data between 24h and 28days, several differences were found relating to time, salinity and the interaction between these factors, depending on the variable analyzed. Water salinity has direct implications for hematological, biochemical, performance and carcass composition of juvenile L. alexandri. Salinities up to 7.5g salt/L for short time periods (96h) to diseases treatments or transport and 2.5g/L in longer time periods (28days) to cultivation indoor can be used for juvenile L. alexandri. •Juvenile of L. alexandri of approximately 28g tolerate salinities up to 7.5 g of salt/L in short baths of 96 hours•The performance of juvenile of L. alexandri is best up to the salinity of 2.5 g of salt/L after 28 days of rearing.•Cortisol, glucose, hematocrit, osmolarity and Cl- ions indicate stress in the management of water salinity for juvenile of L. alexandri•Comparing the hematological and biochemical data between 24 hours and 28 days, several differences were found relating to time, salinity and the interaction between these factors.