Thermal stress altered growth performance and metabolism and induced anaemia and liver disorder in Labeo rohita

Abstract

Sudden fish deaths occurred during summer peaks in India and expected to be more in future. This study was conducted to explain the biochemical responses of Labeo rohita under extreme thermal condition (treated: 37–38°C against controlled: 28–30°C). Exposure of 14 days resulted in 30% of fish mortality. Glucose concentration was maintained in serum for both treated and controlled groups. However, triglycerides, protein, globulin, calcium, cholesterol and haemoglobin were declined and enzymes (glutamate-pyruvate transaminase, GPT and glutamate-oxalate transaminase, GOT) were elevated in serum in the treated group. Indicators of overall metabolism (biomolecules: glucose, triglycerides, protein, cholesterol; enzymes: GPT, GOT; and RNA: DNA) were diminished in liver, whereas these were less affected in muscle. Higher GPT, GOT and lower albumin in serum confirmed disturbance in hepatic panel. Simultaneously compromised growth (lower SGR, DNA content in liver) was observed in treated fish due to impaired metabolism. Extreme thermal stress induced by such catastrophic warmer water exposure caused liver problems and anaemia which ultimately caused fish death.