Anesthetic potential of geranium (Pelargonium graveolens) oil for two cichlid species, Sciaenochromis fryeri and Labidochromis caeruleus

The anesthetic potential of geranium oil (Pelargonium graveolens L.) was evaluated in two freshwater aquarium fish species, the electric blue hap (Sciaenochromis fryeri, 2.00 +/- 0.61 g) and blue streak hap (Labidochromis caeruleus, 2.31 +/- 0.52 g). Fish were exposed to nine concentrations of anesthetic (25, 50, 75, 100, 125, 150, 200, 250, 300 mu l L-1). The induction time generally decreased significantly with increasing concentration of geranium oil for both of the fish species. The recovery time increased with the enhancing geranium oil concentration. Deep anesthesia took between 61.19 +/- 7.25 s and 165.43 +/- 6.78 s for S. fryeri and between 73.32 +/- 8.92 s and 171.12 +/- 10.74 s for L. caeruleus. Recovery occurred after 96 +/- 6.87 s (L. caeruleus), with the longest being 291.45 +/- 8.31 s (S. fryeri). The minimal effective concentration was 75 mu l L-1 for deep anesthesia for both two species, and 50 mu lL(-1) was found as the minimal sedative concentration at the stage of loss of equilibrium. These findings suggested that geranium oil is a new potential anesthetic for two ornamental fish species.