Mass production of juveniles of the fat snook Centropomus parallelus in Brazil

A pilot-scale trial to rear fat Snook Centropomus parallelus through larval, weaning and nursery phases was conducted in Florianopolis, Brazil. Eggs (96% fertilization) from captive broodstock, induced to spawn using 50 mug/kg LHRHa were stocked in two 4,000-L cylindrical fiberglass tanks at a mean density of 19.2 eggs/L. Nannochloropsis oculata was stocked with the eggs and maintained at a mean density of 0.5-1.0 x 10(6) cells/mL up to 31 dph (31 dph). Hatching averaged 90%. Larvae were fed rotifers Brachionus rotundiformis enriched with an oil emulsion from 3 dph to 36 dph (30-40 rotifers/mL) and Artemia meta-nauplii enriched with Selco(R) from 22 dph to 60 dph (mean 2.9 meta-nauplii/mL). Weaning began at 45 dph with an artificial dry diet NRG(R) (50% protein), supplied together with concentrated and enriched Artemia meta-nauplii. No critical period of mortality was observed during larval rearing. During the 43 days of weaning and nursery, less than 1% mortality was recorded. Food conversion rate during nursery was 1.17, with a change in the coefficient of variation of mean total length of 1.3%. Specific total growth rate in weight was 13.0 %/d and mean growth in total length and total weight were 0.65 mm/d and 24.0 mg/d over the whole rearing trial respectively. Mean total length and total weight of juveniles were 57.6 +/- 0.1 mm and 2.11 +/- 0.12 g, respectively, and the length-weight relationship was W = 8.29931 x 10(-5) TL3.049607 (r = 0.9986), on 98 dph when the trial was terminated. The condition factor on 88 dph was 1.104. On 88 dph a total of 35,000 juveniles were harvested, overall survival was 25.5% with mean final density of 4.4 fish/L and biomass of 6.9 kg/m(3). The present trial demonstrated the feasibility of mass production of fat Snook. Possible improvements necessary for commercial cultivation of fat snook C. parallelus are discussed.