Dietary available phosphorus requirement of juvenile walking catfish, C larias leather

A feeding trial was conducted to evaluate the optimum requirement of dietary available phosphorus ( AP ) for juvenile walking catfish, C larias leather . Six practical diets were formulated to contain graded levels (2.2, 3.9, 5.5, 7.1, 8.8 and 10.4 g kg −1 ) of AP from dietary ingredients and monocalcium phosphate. Each diet was randomly fed to triplicate groups of fish with initial mean weight of 7.94 ± 0.08 g in floating cages (1.5 × 1.5 × 2.0 m) suspended in an earthen pond, and each cage was stocked initially with 60 fish. Fish were fed thrice daily (07:30, 13:00 and 17:30) to apparent satiation for 10 weeks. Both specific growth rate ( SGR ) and protein efficiency ratio significantly increased with increasing AP from 2.2 to 5.5 g kg −1 ( P  <   0.05) and then levelled off. Dietary AP levels significantly influenced whole‐body protein, lipid and ash contents as well as condition factor and hepatosomatic index ( P  <   0.05). Whole‐body and vertebrae phosphorus contents showed similar patterns as SGR in response to dietary AP content. Broken‐line analyses based on SGR , phosphorus contents in the vertebrae and whole‐body indicated the AP requirements were 5.8, 7.2 and 7.5 g kg −1 , respectively.