Elevated Carbon Dioxide and Its Impact on Growth, Blood Properties, and Vertebral Column of Freshwater Fish Mahseer, Tor tambroides Juveniles

Abstract

The level of carbon dioxide, which resembles water acidification, is critical to the success of juvenile fish production. The growth, skeletal deformities, and blood parameters of the economically important freshwater fish mahseer, Tor tambroides, were assessed in different concentrations of pCO2 (400, 700, and 1000 µatm pCO2). The highest growth properties (survival rate, body weight gain (BWG), specific growth rate (SGR)) in mahseer were observed at 400 µatm, whereas the lowest growth indices were found in the treatment of 1000 µatm pCO2. The lowest pCO2 concentration was found to be within the optimum healthy blood parameter range. The fish exposed to acidic conditions (700 and 1000 µatm) exhibited considerably higher levels of haemoglobin and haematocrit compared to the control fish. Glucose levels were significantly lower in the acidic conditions, while total cholesterol levels in mahseer fish exposed to acidic conditions were higher. The fish displayed skeleton malformations as the concentration of pCO2 was elevated. The findings from this research could be set as a standard technique in the juvenile rearing of mahseer fish under acidified conditions.