This study evaluated the effects of phytase supplementation in diets containing Aspergillus niger fermented oil palm leaf meal on the growth performance, feed utilization, protein retention, and survival of snakeskin gourami, Trichopodus pectoralis Regan, 1910. A completely randomized design was applied with three dietary treatments containing phytase at 300, 500, and 700 mg kg⁻¹, each with three replicates. Fish (initial weight 5±2 g) were reared for 56 days and fed twice daily at 5% of biomass. Data were analyzed using one-way ANOVA. Phytase supplementation significantly affected absolute growth, relative growth rate, feed conversion ratio (FCR), feed efficiency, and protein retention (p < 0.05). The diet supplemented with 700 mg kg⁻¹ phytase resulted in the highest absolute growth (4.07 g), relative growth rate (45.84%), feed efficiency (24.20%), and protein retention (24.02%), and the lowest FCR (4.65). Survival rate ranged from 90 to 100% and did not differ significantly among treatments (p > 0.05). These results indicate that supplementation of 700 mg kg⁻¹ phytase in diets based on fermented oil palm leaf meal improved growth and feed utilization of T. pectoralis within the tested range.
