Weaning from live food Moina minuta to inert diet during the first feeding of angelfish (Pterophyllum scalare - Schultze, 1823) and severum (Heros severus - Heckel, 1840)

The aim of the present study was to determine the optimal time to start weaning from Moina minuta to inert diet, assessing its effects on growth performance, stress resistance, feeding cost and intestinal histomorphometry of angelfish and severum during larviculture. Two separate 30-day experiments were conducted with 200 post-larvae each of angelfish ( Pterophyllum scalare ) and severum ( Heros severus ). At five days post-hatching, angelfish and severum had an average initial length and weight of 5.58 ± 0.13 mm and 1.72 ± 0.26 mg, and 6.38 ± 0.25 mm and 3.02 ± 0.27 mg, respectively. The larvae were distributed in twenty 1 L aquariums at a density of 10 post-larvae per liter. The experiments included five treatments with four replications, consisting of five supply periods of M . minuta for 0, 5, 10, 15 and 20 days (T0, T5, T10, T15 and T20), followed by a three-day weaning period (50 % M . minuta and inert diet) and then feeding only inert diet. The highest values of final length, length gain, final weight, weight gain, specific growth rate for both length and weight were observed in both species in T15 and T20. Only angelfish post-larvae had a higher value of survival rate when submitted to T15 and T20, and a higher stress resistance to air exposure when submitted to T10, T15 and T20. Both species had the lowest feeding costs in T20. Angelfish and severum post-larvae in T15 and T20 showed the highest value of intestinal villus height and perimeter. Severum post-larvae in T10, T15 and T20 had the best value of villus width. Angelfish post-larvae in T0 and T5 had the highest proportions of goblet cells, while severum post-larvae exhibited this only in T0. It is recommended that angelfish and severum post-larvae be fed with M . minuta for 15 days before weaning. • Angelfish and severum post-larvae may fed Moina minuta for 15 days before weaning. • Lower feeding cost by 18.99 % for angelfish fed with Moina minuta for 15 days. • Lower feeding cost by 19.19 % for severum fed with Moina minuta for 15 days. • Feeding with Moina minuta for 15 and 20 days improves resistance to stress. • Feeding with Moina minuta for 15 and 20 days improves intestinal histomorphometry.