Abstract
The behavior and feeding habits of different sizes of hatchery-reared tiger puffer fish Takifugu rubripes were investigated. Five juveniles of each size group (3.2±0.2 cm, 4.9±0.2 cm, 6.2±0.3 cm, 9.5±0.5 cm SL) were placed in a tank containing 32 psu water (control) and a tank containing salinity-gradient (10-32 psu) water, and the vertical distribution (surface, middle, bottom) of the fish was determined after 3 h. Large juveniles (6.2±0.3 cm and 9.5±0.5 cm SL) swam to the surface layer of the salinity-gradient tank more frequently (27-89%) than the control tank (4-51%) during 1-3 h after transfer. The settling behavior of juveniles (5.5±0.3 cm and 10.9±0.7 cm SL) at 15 and 32 psu, and using static and spring water was also investigated. Settlement rate of small (5.5±0.3 cm SL) juveniles was significantly lower (P<0.0001) than large (10.9±0.7 cm SL) juveniles. Spring-water and 15 psu stimulated settlement in both sizes. Feeding preference of puffer fish juveniles (5.4±0.6 cm, 8.9±1.0 cm SL) with or without sand as substrate was also investigated. Fish showed active feeding without sand, and 83% of the large juveniles (8.9±1.0 cm in SL) fed on bivalves, while only 42% of that small juveniles (5.4±0.6 cm SL) fed on bivalves. Overall results showed that hatchery-reared tiger puffer juveniles prefer low salinity (10-16 psu) environment, became benthic as the size increases, and eat benthic food item like bivalves when they are over 6 cm in SL.
