Effect of Water Temperature on Survival, Growth and Molting Cycle During Early Crablet Instar of Mud Crab, Scylla paramamosain (Estampador, 1950)

This study aimed to determine the effect of rearing water temperature on survival, growth and molting cycle of the mud crab, S. paramamosain from Megalopa up to 1st crablet instar (Crablet 1) and from Crablet 1 to 2nd crablet instar (Crablet 2). Different water temperature regimes were implemented i.e. 20 °C, 24 °C, 28 °C, 32 °C, 36 °C and ambient temperature. The observed parameters were: successful molting from Megalopa to Crablet 1 and from Crablet 1 to Crablet 2, survival in Crablet 1 and Crablet 2, growth (carapace increment of crablets), Specific Growth Rate of carapace width (SGRCW) and, molting interval (in days) from Megalopa to Crablet 1 and from Crablet 1 to Crablet 2. The results showed that the highest survival rate from Megalopa to Crablet 1 was found at 24 and 28 °C where both could reach up to 100%. At water temperature of 32 °C and ambient temperature, the survival rate were 96.66%. The lowest survival rate was found at 20 °C and 36 °C treatments (p   0.05), but there were significant differences in molting intervals (p < 0.05) for both Megalopa to Crablet 1 and Crablet 1 to Crablet 2 phases. Treatment of ambient temperature (27–30 °C) had the fastest molting interval from Megalopa to Crablet 1 but its value not significantly different with treatment of 24, 28 and 32 °C. The fastest molting interval from Crablet 1 to Crablet 2 was found at 32 °C which was 2.96 days (p < 0.01). Based on this study, it is recommended that rearing from Megalopa to Crablet 1 should take place at a temperature of 28 °C while, in Crablet 1 to Crablet 2 phase, a temperature of 28 to 32 °C is recommended.