Effects of aeration afternoon and its interaction with storage density on water quality and growth of juveniles of Nile tilapia (Oreochromis niloticus)

• Autor(a) principal: Francisco Roberto dos Santos Lima
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFC
• Texto Completo: http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14331
• topic: TilÃpia (Peixe); Aquicultura; Ãgua; Qualidade; Tilapia (Fish); Aquaculture; Water; Quality; ENGENHARIA DE PESCA

The work consisted of two complete and following experiments. In the first study the objective was to verify the efficiency of the afternoon aeration in removing ammonia from Nile tilapia juveniles culture tanks. For this, four treatments with five repetitions each were adopted (8 fish per tank of 250 L; 1.03 Â 0.02 g). The negative control tanks have not received any aeration over the entire study. The schedules of daily aeration for the night aeration, afternoon aeration and afternoon plus night aeration treatments were the followings: 22:00 â 06:00h; 10:00 â 18:00h and 10:00 â 06:00h, respectively. The concentrations of dissolved oxygen in water decreased in the non-aerated tanks and in the afternoon aerated tanks. The afternoon tanks had lower concentrations of NH3 than the non-aerated tanks (p<0.05). Fish stocked in the night aeration tanks and in the afternoon plus night aeration tanks exhibited a higher weight gain than the others (p<0.05). It was concluded that the association of night aeration with afternoon aeration brings more benefits to the water quality in aquaculture than those elicited by the single use of the same managements. In the second study the objective was to verify the effects of the interaction between the afternoon aeration of the water and the stocking density of Nile tilapia juveniles (initial body weight = 1.36 Â 0.03 g) on variables of water quality and growth performance. The fish were stocked in three densities (8; 12 and 16 fish per tank or 32; 48 and 64 fish m-3), and subjected to two aeration systems of water, absence (control; three replicates) and afternoon aeration (four replicates). The afternoon aeration was carried out from 12:00 up to 18:00h (6h aeration day-1) from the third week until the end. Except by the 16-fish tanks, the lowest concentrations of total ammonia nitrogen and non-ionized ammonia were observed in the tanks with more fish and afternoon aeration (P<0.05). The concentration of nitrite was affected by the stocking density as well as by the afternoon aeration (P<0.05). Significant effects upon the growth performance variables were observed only due to the âstocking densityâ factor. It was concluded that in intensive systems, the afternoon aeration of the fish culture water is an efficient water quality management to remove gaseous ammonia and nitrite from the water.