The aim of this study was to assess the leaf aqueous extract composition of green tea (GT) (Camellia sinensis) on growth performance, feed efficiency, hepatosomatic index (HSI), gonadosomatic index (GSI), and viscerosomatic index (VSI) in convict cichlid (Amatitlania nigrofasciata). For this purpose, fish (initial mean weight, 1.28±0.02 g) were divided into five groups: GT₀ (0 mg green tea extract kg^-1 of feed), GT₅₀ (50 mg green tea extract kg^-1 of feed), GT₁₀₀ (100 mg green tea extract kg^-1 of feed), GT₂₀₀ (200 mg green tea extract kg^-1 of feed), and GT₄₀₀ (400 mg green tea extract kg^-1 of feed). Each treatment had triplicate groups and, in each replicate, there were 15 fish fed to satiety for 84 days. Fish weight and length were measured every 21 days and at the end of trial growth parameters, including specific growth rate (SGR), weight gain (WG), condition factor, daily growth rate (ADG), and nutritional factors including food intake (FI), feed conversion ratio (FCR), as well as HSI, GSI and VSI were measured. The results showed that in GT₁₀₀ treatment, SGR (1.97±0.04 %/day), WG (5.53±0.07 g) and ADG (0.98±0.01 g/day) was greater than the other groups (P<0.05). Moreover, the greatest and lowest FI were observed in GT₁₀₀ (5.64±0.07 g) and GT₂₀₀ (4.91±0.09 g), respectivly (P<0.05). Also, the best FCR was observed in GT₁₀₀ treatment (P<0.05), but there was no significant difference in HSI, GSI and VSI among trial groups (P>0.05). The results of this study showed that the use of 100 mg/kg of green tea extract in convict cichlid feed can improve growth performance and nutritional indices.