Influence of the anaesthetic quinaldine on some tilapias

Three species of tilapia, Sarotherodon melanotheron and Sarotherodon guineensis from brackish water and Oreochromis (Sarotherodon) niloticus from fresh water, were exposed to different concentrations of the anaesthetic quinaldine to determine the safe level for handling and transportation of these species. It was observed that the time taken to lose balance increased with a decrease in the concentration of the anaesthetic. This was probably due to the very low concentration of the hydrogen ions in the progressively diluted test media. Dosages of quinaldine for handling fish for experimental work and for transportation are given with the proviso that the anaesthetization is carried out under conditions of salinity and temperature which are suitable for acclimation.