Effects of weaning on survival and growth of silver therapon ( Leiopotherapon plumbeus ) larvae fed live and artificial diet

This study examined the effects of early weaning strategies on growth and survival of the silver therapon Leiopotherapon plumbeus larvae. In Trial 1, four larval age groups (8, 14, 20 and 26 days post-hatch (dph)) were abruptly weaned to commercial powdered tilapia diet and compared with wild copepod-fed group as the control. In Trial 2, another batch of three weaning age groups were subjected to gradual weaning (8 dph larvae with 8 days co-feeding, 14 dph larvae with 6 days co-feeding and 20 dph larvae with 4 days co-feeding) with Artemia nauplii prior to weaning on commercial powdered prawn diet and compared with a control group consisted of larvae fed exclusively on Artemia nauplii. Both weaning trials were conducted for 21 days. A gradual weaning strategy promoted better survival (22.2%–40.0%) among weaning age groups than the abrupt weaning strategy (2.2%–36.7%). Except for those weaned at 26 dph, abrupt weaning resulted in significantly poor growth and survival among all weaning age groups compared with the wild copepod-fed control group. The highest survival and growth were observed in 20 dph larvae with 4 days live food co-feeding, although the values were significantly lower than the Artemia-fed control group. These results suggest that abrupt weaning at 26 dph, and gradual weaning for 4 days from 20 dph promote successful rearing of silver therapon larvae and that a microparticulate diet specifically formulated for this species needs to be developed.