Improving Salinity Tolerance in Tilapias: Past Experience and Future Prospects

With increasing scarcity of fresh water available for aquaculture, especially in arid regions, development of tilapias that tolerate high salinity would increase fish (and hence, animal protein) production. We review culture practices, nutrition, physiology, and genetics, and propose approaches to improving salinity tolerance in tilapias. Physiological studies of biochemical pathways underlying phenotypic differences in salt tolerance can lead to genetic studies of intra and interspecific variation. Molecular technology can lead to studies on osmoregulation-related biochemical pathways, for which the euryhaline tilapia is an attractive model. Functional genomics and proteomics are powerful tools for studying the molecular bases of environmental adaptation and metabolic connections to osmoregulatory physiology. Both provide avenues for discovering novel pathways related to osmoregulation with relevance to aquaculture. Dietary supplementation with NaCl and optimized acclimation protocols are immediate and practical ways to improve salt tolerance. Inter-specific variation in salinity tolerance may be used to select salt-tolerant species and develop salt-tolerant hybrids. In the long term, quantitative trait loci associated with, or genes involved in, saltwater tolerance may facilitate marker-assisted or gene-assisted selection for this trait in tilapia.