ABSTRACT
Promotion of aquaculture in Zambia has contributed to the exploitation of different culturing systems and species. This promotion has led to utilization of intensive systems which are associated with high stocking densities and poor water quality, a scenario that renders fish to high risk of diseases characterized with clinical signs such as tail and fin rot, gill rot, red spot and dropsy. In Zambia Saprolegniosis has been a serious threat to the aquaculture industry. Therefore, this study evaluated possible treatments for saprolegnia in aquaculture in Zambia following its identification. The objective was to investigate Saprolegnia occurrence in diseased fish and elaborate on possible preventive treatment. The investigation was carried out by isolating and identifying Saprolegnia using phenotypic methods followed by a treatment regime of boric acid.
A total of 20 fish of each species (Oreochromis andersonii and Clarius gariepinus) showing signs of Saprolegniosis were picked from the culture systems and postmortems conducted on site and organs were extracted for media culture on Sabouraud dextrose agar (SDA). Saprolegnia was seen growing on Oreochromis andersonii specimens while no growth was observed on Clarius samples. At farm level the same number of fish were exposed to different levels of Boric acid concentrations ranging from 0.2g/L, 0.4g/L, 0.6g/L and 0.8g/L for 10days. It was observed that in the tank with a concentration of 0.8g/L, complete recovery.
In conclusion results from this study will help fill the knowledge gap on effective control of Saprolegnia in Oreochromis andersonii and Clarius gariepinus cultured for increased productivity as there will be few losses of fish resulting from disease.