Embryonic and first larval developmental stages of the fat snook Centropomus parallelus Poey (Pisces, Centropomidae), with interest for aquaculture

Abstract

The embryonic and first larval developmental stages of the snook Centropomus parallelus Poey are described based on samples of eggs and larvae collected during induced spawning and larval rearing experiments in 1998 at Florianópolis, Brazil. Both embryonic and larval development are very similar to those of other snooks, specially Centropomus undecimalis. The eggs are pelagic and spherical (0.67 ± 0.01 mm in diameter), transparent, smooth corium without sculptures, and with one oil droplet (0.20 ± 0.02 mm in diameter). Hatching occurred 22-23 hr after fertilization at 25ºC. Newly hatched larvae are small, 1.85 ± 0.08 mm in total length. At 26 ± 1ºC larval developmet was more closely related to size than to age. Mouth was functional from the third to the fourth days of age and the yolk sac and oil droplet were completely consumed at 5 days of age. Notochord flexion occurred between 3.55 and 4.20 mm of total length. Mouth width (Bc) was initially 220 mm and increased linearly with age (E)(in days) and with total length (LT)(in mm) expressed by equations: BC=0.2104 + 0.0395 E (r=0.9619) and Bc=-0.1483 + 0.1566 LT (r=0.9880) respectively. The postlarval transformations to juvenile stage was extended after the age of 40 days and a total length bigger than 10 mm. Four larval growth periods were observed, the first three were linear with 0.32, 0.06 and 0.18 mm/day and the fourth was exponential, with 0.22 mm/day between day 15 and day 30 of age.