SOME FACTORS AFFECTING THE RESPIRATION OF GRASS CARP, CTENOPHARYNGODON IDELLA, CUVIER AND VALENCIENNES

Abstract

The study investigated the respiratory movements and influence of some environmental and intrisic factors on the respiration of the grass carp, Ctenopharyngodon idella, cuvier and Valenciennes. Ventilation volume, ventilation rate and ventilatory stroke volume of the grass carp were each positively correlated with its body weight with correlation coefficients of 0,873, 0,327 and 0.869 respectively. The effect of temperature on the above mentioned respiratory parameters were found to be positively and significantly (P < 0.05) correlated. Fish respired normally with optimum ventilation volume and ventilatory stroke volume at an optimal pH of pH 7.0. A very strong correlation (correlation coefficient 0.7 - 0.9) between ventilation volume and ventilatory stroke volume indicated that the grass carp generally varied stroke volume of the buccal pump rather than frequency of breathing to adjust ventilation volume. The oxygen consumption of the grass carp was determined at 15, 20, 25 and 30°c by using the 'sealed container method'. It was found that oxygen consumption rates increased with temperature which also implied an increase in metabolic rate with temperature. The Q10 value was found to be approximately 2.0. Oxygen consumption rate and oxygen utilization of grass carp decreases with increasing flowrates across the gills. Opercular movements of the grass carp was negatively correlated with flowrate.