The aim of this study was to evaluate the dietary crude protein requirements of juvenile Betta splendens . Isocaloric diets were used with six levels (27, 31, 35, 39, 43 e 47%) of crude protein (CP) in entirely randomised design with four repetitions. Fish with an average weight of 0.11 ± 0.02g were fed three times a day for 30 days. At the end of the experiment were evaluated: survival rate (SR); weight gain (WG); feed intake (FI); protein intake (PI); feed conversion (FC); protein efficiency ratio (PER); and specific growth rate (SGR). For FI, FC and PER, a negative linear effect of dietary CP levels was observed (p < 0.05). A quadratic effect of dietary CP levels for SR, WG and SGR was also observed and the estimated values which maximise the respective parameters were 30.95, 33.13 and 29.55% of CP. Thus, we concluded that the requirement for protein for juvenile Betta splendens is between 30 and 33% CP.