Chapter 16: Growing Invasive Fish in Sewage-Fed Ponds to Improve Water Reuse and Food Security

Invasive fish species can be successfully grown in sewage-fed fish-ponds, especially treated sewage ponds. Fish species commonly grown in sewage fish ponds are bighead carp (Hypophthalmichthys nobilis), silver carp (Hypophthalmichthys molitrix), Nile tilapia (Oreochromis niloticus), grass carp (Ctenopharyngodon idella), common carp (Cyprinus carpio), and catfish species, such as African catfish (Clarias gariepinus) and walking catfish (Clarias batrachus). These fish are known to be invasive or potential invasive species and can tolerate extreme environments, such as those with high temperatures and wide ranges of salinity, pH, dissolved oxygen, and ammonia. Among the fish used in sewage-fed fishponds, tilapia exhibit the best survival in sewage. However, inorganic pollutants (heavy metals), organic pollutants (such as pesticides), and pathogens (such as bacteria, viruses, and parasites) in sewage cause morphological and physiological alterations in organs. Fortunately, these sewage pollutants mainly accumulate in the viscera (especially the liver and gill) and less in the muscle (the edible part of the fish). Furthermore, these undesirable pollutants and pathogens are generally within ranges suitable for human consumption. The information in this chapter is expected to serve as a reference for the management of invasive fish species.