Energetic balance in Chirostoma estor estor (Jordan, 1879) (Pisces, Atherinopsidae) juveniles in relation to size

Abstract

In this work we determined the energetic flow in juveniles of Chirostoma estor estor (Jordan, 1879) of two classes of weight (P < 0.05). We had two groups A and B, both were selected by weight 1.50 ± 0.22 g and 3.30 ± 0.29 g. respectively. The fish were maintained at 20 °C, were feed to the 4% of wet weight, with a commercial balanced diet (28% of protein). The physiological responses were measured and integrated in o the equation of energetic balance in order to estimate the potential energy for growth or scope for growth that would be channeled to somatic growth. Independently to the weight, the scope for growth was 80% of energy incorporated with the ingested food; the losses of energy through feces and nitrogen excretion reached 6.88 and 3.65 % of extracted energy from the ingested food, respectively. Energy used in aerobic metabolism corresponded to the 9.42%. The models that describe the oxygen consumption rate (R) of the fish were A: R = 0.246 W0.91 and B: R = 0.501 W0.91 (P < 0.05; R2 = 0.884). This indicates that the oxygen consumption rate do not vary in relation to the weight interval, however the intensity of the rate increase in a 50% in the organisms of larger size. The data provided is important to improve the culture practices of the species.