Feeding protocol for the Amazonian ornamental cichlid Apistogramma cacatuoides and a histological approach to the nutritional condition of larvae

The aim of this study was to develop a feeding protocol for the larviculture of Apistogramma cacatuoides, using the histological approach to larval nutrition conditions. For this, three experiments were carried out. Experiment 1 was carried out in a randomized design to determine the optimal amount of Artemia nauplii (AN) per larva, and three treatments were evaluated: P1—feeding with 25 A. nauplii per larva (AN/L) during the first 5 days, followed by 50 AN/L from the 6th to the 10th day and 100 AN/L from the 11th to the 20th day; P2 and P3—37 and 50 AN/L during the first 5 days, 75 and 100 AN/L from the 6th to the 10th day and 150 and 200 AN/L from the 11th to the 20th day. Experiment 2 was carried out in a randomized design to determine the daily frequency of feeding and evaluated four feeding frequencies: F1—feeding only once a day (09:00); (F2)—feeding twice a day (09:00 and 17:00); F3—feeding three times a day (09:00, 11:30 and 17:00); and F4—feeding four times a day (09:00, 11: 30, 14:00 and 17:00). Experiment 3 lasted 40 days and was conducted in a randomized design to evaluate three periods for the beginning of the feeding transition: WE10:AN for 10 days, followed by 3 days of co-feeding and commercial feed until the end of the experimental period; WE15:AN for 15 days, followed by 3 days of co-feeding and commercial feed; WE20:AN for 20 days, followed by 3 days of co-feeding and commercial feed. The results of this study showed that, for the best development of the larvae, they should receive the feeding protocol 50−100−200 AN/L (P3) until the 20th day of exogenous feeding. From the 21st day, the transition to inert food should begin with 3 days of co-feeding, and feeding during larviculture should be carried out at a frequency of twice a day; this protocol provided a good nutritional status for the larvae, as shown by the histological approach.