<b>Effect of temperature on growth and survival of juvenile mullet Mugil platanus Günther, 1880</b>

Abstract

The mullet Mugil platanus is one of the most important commercial species from Lagoa dos Patos estuary and a promising specie for marine fish culture. This study was designed to determine the influence of temperature on growth and survival of mullet juveniles. Fish of about 0.87g initial body weight were distributed in 50L tanks, at an initial stocking density of 1 mullet/L. Three temperatures were tested in triplicate: 20, 25 and 30°C. The mullets were fed on commercial diet (28% crude protein), the diet was triturated and the fraction between 0.85 to 1.18mm diameter was used. Feeding was ceased when food started to accumulate on the bottom of the tanks. After 28 days of rearing, it was observed that growth was directly proportional to temperature, presenting average length and weight equal to 5.09, 5.44 and 6.39cm and 1.82, 2.07 and 3.13g at 20, 25 and 30°C respectively. Daily specific growth rate was 2 .64% (20°C), 3.26% (25°C) and 4.31% (30°C). Apparen t food conversion rate was inversely related to temperature, it was equal to 2.11, 2.60 and 3.17 at 30, 25 and 20°C respectiv ely, demonstrating a better use of the diet at increasing temperatures. Survival was not affected by temperature, it was equal to 99% (20°C), 100% (25°C) and 94% (30°C). According to these results, juvenile mullet can be reared at 30°C in order to o ptimize growth.