Feeding, metabolism, and growth of tropical flatfish

Abstract

Observations have been made during a 3-month period on the growth, feeding and metabolism of five species of Cynoglossus from the Arabian Sea on the southwest coast of India; two other types of sole, Brachirus and Synaptura were also studied. Growth increments of samples of Cynoglossus taken at regular intervals from the sea varied between 0.9 and 2.0 mm per week. From samples taken throughout a 24-h period in the sea, there is evidence of a diel feeding rhythm with the greatest activity at night. Measurements of standard oxygen consumption at 28 °C indicated a relationship between oxygen consumption ( Q; mg O 2/ h) and live weight ( W; g) of, Q = 0.372 W 0.734 for Cynoglossus and of Q = 0.362 W 0.682 for Brachirus and Synaptura. The standard oxygen consumption of Cynoglossus was temperature-dependent between 15and 30°C, but temperature-independent between 30 and 37.5 °C, where a plateau of oxygen consumption was observed. Cynoglossus were fed at 28 °C with the polychaete Diopatra neopolitana Delle Chiaje: a maintenance food intake of 25% of the body weight per week was indicated. The metabolic level, as indicated by the oxygen uptake, of the fish was related to food intake, being highest at the highest feeding levels. Efficiencies of conversion of assimilated food into growth of 11 to 12% were observed.