Utilização da arthrospira platensis como suplemento alimentar para melhorar o desempenho da tilápia do nilo (Oreochromis niloticus) em sistema de recirculação de água salgada

Abstract

Aquaculture uses various natural resources; one of them is water, which should be used rationally so that the activity is perennial and profitable. Euryhaline fish species, such as Nile tilapia, in brackish or marine systems are able to provide animal protein in places where fresh water is scarce. For that, introducing new species or adapting new cultures already existent, you can seek a diversification of aquaculture practices to start a sustainable maintainability. One solution to alleviate these ecological problems in tilapia culture is a recirculation system, which has a primarily characteristic of water reuse. Moreover, many researches have been performed utilizing Arthrospira platensis as a food supplement in the diet of many aquatic organisms, since it is a rich source of protein. Thus, the objective of this study was to evaluate the use of A. platensis as a food supplement to improve the performance of Nile tilapia (Oreochromis niloticus) in salt water recirculation systems. Two treatments were developed with four replications each, totalizing four polythene containers with capacity of 100 L. Each culture lasted 45 days, for both controlling and testing, totalizing 90 days. For controlling was offered commercial ratio, and for testing was offered commercial ratio with an increase of 20% of A. platensis flour. Analysis of water quality, growth performance and chemical composition of fish fillet were performed. The water quality results presented that ammonia (NH3), nitrate (NO3-) and phosphate (PO43-) remained above the ideal range, outside of nitrite (NO2-). The treatment that received supplementation of A. platensis had larger values. In relation to growth performance, most of the variables did not show statistically significant difference between treatments; except for the specific growth ratio and survival in which were higher in control. On the other hand, for chemical composition of fish fillet, the treatment that received supplementation with A. platensis presented an increase of protein levels. Consequently, that it is possible to grow Nile tilapia in salt water with salinity of 35 ppt without change the performance of the fish, thus the cultivation of this species becomes viable in salt water or even brackish. Therefore, it is considered a great alternative to the time of freshwater shortages that we are living.