The research was conducted to identify the infection level of fish-lice (Caligus spp) on Rabbitfish (Siganus guttatus) which cultures in Thua Thien Hue province, and to clarify the effect of extraction from Saudau (Azadirachta indica) plant on the fish lice. The total of rabbit fish that were used for experiments is 120 fish, and fish were collected in 6 months at two different sites. The extraction of the Saudau plant was collected from leaf, and seed and then concentrated for experiments at ppm (0; 10; 50; 100; 500; and 1000) to evaluate the effect of extraction on fish lice. The results showed that the infection rate of fish lice on rabbit fish is 62,5% and infection intensity averaged at 19,2 lice/fish. Based on the collection data, it was clearly shown that in January, February, and March, fish lice were found much more than in other months (p<00.05). After fish lice were treated with the extraction from leaf and seed for 30 hours, we found that the half effective concentration (EC50), and 90% effective concentration (EC90) of leaf extraction are 148ppm and 928ppm, respectively. The EC50 and EC90 of seed extraction are 62ppm and 397ppm, respectively. The results from our research frankly show the potential of using extraction from Saudau leaf and seed to treat the parasite disease caused by fish lice on Rabbitfish.
Keywords: fish-lice, rabbit-fish, Saudau, effective