This investigation aimed to analyze the effects of different diets and determine the optimal feed on the growth performance of guppy Poecilia reticulata (Peters, 1859). In the present study, juvenile guppies were procured from commercial fish breeders, Kolathur, Chennai, and fed with four experimental diets, namely Diet I (Control-Pellet feed), Diet II (Formulated feed), Diet III (Dry Tubifex), and Diet IV (Live feed Brachionus plicatilis) to examine the effects on growth and survival rates. In the experiment, 12 glass circular tanks with a volume of 10 L were used, and ten juveniles having an average body length and weight of 0.8 cm and 0.01 g were randomly introduced into each aquarium (80 cm×30 cm×35 cm) in triplicates. During the experimental study, the fish were fed two times a day ad libitum for 90 days. The various growth parameters and proximate composition of the diets were calculated by following standard methods. The findings showed significant differences (p<0.05) in the fish's various growth parameters fed with different diets. The fish fed with Diet IV 52% crude protein performed better than those provided with lower levels. The increase in growth parameters could be attributed to increased levels of dietary crude protein. However, the diet does not have any significant impact on fish survival rates. Thus, it is concluded that the Live Feed B. plicatilis with 52% crude protein is suitable for the
optimum growth of Poecilia reticulata under the current experimental set-up and recommended for feeding juvenile guppies.