Anaesthetic and Histological Effects of Lidocaine Hydrochloride on Oreochromis niloticus Juveniles

This study investigated the toxicity of Lidocaine Hydrochloride-sodium Bicarbonate (LHB) on Oreochromis niloticus juveniles (20.75 g). The histological tissue examinations were used to assess the effects of the anaesthetic agent (LHB) on the fish after exposure. Varying concentrations of LHB in increments of 10mg/L ranging from 60mg/L to 100mg/L were used for the static bioassay. There was a decrease in induction and recovery time with an increasing concentration of LHB showing a significant positive correlation (R2= 0.9721; p<0.05) and (R2=0.7338; p<0.05) respectively. Anaesthetic values of LHB for O. niloticus at an induction time of less than 4 minutes and recovery time of less than 3 minutes were observed. No mortality occurred during the experiment. Histological examination of the gills, liver and kidney of O. niloticus after exposure showed different pathological changes. The gills and liver of the fish exposed to 100 mg/L concentration showed no sign of histological changes. However, the results obtained showed a severe histological effect on the kidney of juveniles Oreochromis niloticus at 100 mg/L of LHB.