Behaviour study of Lates calcarifer and Caligus sp. treated with methanolic extract of melalueca cajuputi

Abstract

This experiment determined the effect of Melalueca cajuputi extract to behaviour of juvenile sea bass, Lates calcarifer and Caligus sp. The 96h static bioassay experiment was conducted to determine the median lethal concentration (LC5 0) for L. calcarifer to M cajuputi methanolic extract. One hundred twenty L. calcarifer measuring 7.5 - 9.0 cm total length and 10.0 - 15.0 g were used for the experiment. Ten tanks were filled with 40 L aerated dechlorinated water and the salinity range between 12 ppt to 15 ppt. The M cajuputi methanolic extract was introduced at different concentrations (80 mg/1, 90 mg/1, 100 mg/1, 110 mg/1, and 120 mg/1). The 96h - LC50 of M cajuputi methanolic extract to juvenile is 102.06 mg/I with 95% confident limit of 89.25 - 118.18 mg/1. The changes behaviour exhibited by the fish includes agitated behaviours ( aggression, stunned posture, frequent surface to bottoms movements, erratic swimming), respiratory distress (air gulping, vertical posture with exposed snout, excessive mucus secretion) and abnormal nervous behaviours (sluggish and swilling movement, state of motionless, sudden darts, different postures). The agitated behaviour, respiratory distress and abnormal nervous behaviour increased with increased concentration of the M cajuputi methanolic extract and time of exposure. The Caligus sp. behaviour changes and death were observed during M cqjuputi extract test. Results of the tests provided an information of using M cajuputi extract as an antiparasite agent in controlling ectoparasite on sea bass.