Avaliação da dieta e crescimento de tilápias produzidas em reservatórios de água para irrigação em pequenas propriedades rurais

Abstract

The tilapia farming in lined ponds stimulates aquatic natural organisms populations due to eutrophication as water-flows are very low, and feeding are artificial and complete. These organisms by the fish are consumed complementing the artificial diet, and the fish farming effluents can be used for pasture fertirrigation in integrated milk production system. The objective of this study was to analyze the diet and growth of tilapia during a productive cycle, as well as the water quality of tilapia cultivation in irrigation reservoirs. The study was carried out in four water reservoirs from November / 14 to June / 15. Fifteen fish were collected per reservoir / month, the morphometric measurements were recorded, the stomachs were removed for qualitative quantitative analysis of the diet and the volume and frequency of occurrence of each food item were calculated. The water quality parameters evaluated were dissolved oxygen, temperature, transparency, pH and electrical conductivity. The dietary items most consumed by the fish during the study were artificial feed, which contributed with the contribution of nutrients favorable to the growth of algae and Chlorophyceae algae, especially the genus Coelastrum, Pediastrum and Scenedesmus, and to these fish were attributed the highest values of weight. Tilapia that had low weight gain consumed more dinoflagellates and diatom algae and during their cultivation the lowest values of dissolved oxygen were recorded. The system produced comercial fish at similar time and weight observed in earthen ponds and his effluents could irrigate the grass for a integrated livestock activity (milk production) in the same farm. The results enable the tilapia farming in the lined ponds but following the best possible management practices.