Adaptation to various forms of culture, and resistance to environmental change are among the characteristics that justify the wide use of Nile tilapia in fish farming. Because it is an excellent candidate for culture in low-salinity water, the production of tilapia in saline environments is a reality in countries such as Taiwan, the Philippines and Malaysia, which are among the largest producers in the world (FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS, 2016).
The species Oreochromis niloticus displays good development at salinities of 0 to 18 g L-1 without impairing its survival . However, when this species is grown in seawater (> 30 g L-1) its growth is reduced by 60%.
There are certain differences between studies,possibly due to experimental conditions and animal size, since other authors have reported salinities of over 20 gL-1 as harmful to the species , while more recent studies have obtained satisfactory results at salinities up to 25 g L-1. Among producers, it is believed that a salinity of 20 g L-1 should be the recommended limit.
The addition of fish that can tolerate culture at moderate salinities in systems that allow the reuse of water, is a viable alternative for regions with salinized waters and low rainfall, as well as for polyculture and culture diversification.
Biofloc Technology (BFT) fits into this context by allowing the reuse of water throughout the culture cycle, thereby requiring minimal or no exchange of water. The benefit of this technology is mainly related to the nutritional value of the biofloc produced in situ. In addition, there is a variety of positive aspects to culture using biofloc, including an increase in production indices , high rates of survival and animal welfare, by guaranteeing acceptable levels of hematological parameters. Other studies also refer to the good water quality provided by bacteria that colonize the biofloc within the production system.
Some studies report on the effects of salinity in the water used in the culture of Nile tilapia associated with the biofloc system. Therefore, due to the need for a technology that minimizes environmental impact, and the increasing demand for animal protein, the aim of this study was to evaluate the effect of salinity on the performance of Nile tilapia (Oreochromis niloticus) cultured in a biofloc system.
Source: Revista Ciência Agronômica, v. 50, n. 2, p. 267-275, abr-jun, 2019.