Integrated multitrophic aquaculture in ponds using substrate for periphyton as natural source of food

As a productive and sustainable alternative to fish farmers, the present study aims to evaluate the use of substrate for periphyton growth in an Integrated Multitrophic Aquaculture (IMTA) with complementary species. The studied species were: Nile tilapia (Oreochromis niloticus), grass carp (Ctenopharyngodon idella) and curimbatá (Prochilodus lineatus). The experiment had four treatments with three replicates that evaluated the IMTAs: [T100] Cb:C – tilapia inside hapas fed on recommended feed, with grass carp and curimbatás outside the hapas making use of natural food; [T50] Cb:C – the same species distribution with tilapia fed 50 % of the daily amount of commercial diet. Cb:C 100 and Cb:C 50 – grass carp and curimbatás fed on recommended feed at two feeding rates (100% and 50%) with substrate for periphyton growth in the feeding restriction treatment. In phase II, tilapias were included in all the treatments as a complementary species. Growth performance of fish and physical-chemical parameters of water were evaluated. In the proposed models, the species were efficient in utilizing the feed and in nutrient cycling, achieving productivity of 6 t/ha in the system without water renewal. Inserting secondary and complementary species reduced the feed conversion ratio (FCR) to values of 0.95 in systems under feed restriction and 1.28 in the groups that received 100% of commercial feed. Considering the reduction of the FCR and the high productivity, farmers can diversify their products in the same area without increasing inputs.