Abstract
Trichodinosis, an ectoparasitic infestation caused by ciliated protozoa-Trichodina spp., is commonly found in skins and gills of freshwater fishes and causes a significant economic loss of fish farming. Synthetic chemicals are widely used to eliminate trichodinosis but it poses a potential risk to environment. The aim of this study is to develop of a new alternative approach by using a natural and environment-friendly material, such as bead tree (Melia azedarach L.) leaf extract for treatment of trichodinosis in whitespotted freshwater catfish (Clarias fuscus). The ethanol leaf extract (EtMA) was obtained via ultrasonic assisted extraction (30 ºC, 90 min). The preliminary phytochemical screening confirmed the presence of some bioactive compounds in the extract, including alkaloids, tannins, saponins, phenolic compounds, steroids, terpenoids and flavonoids. In the in vitro experiment, all of doses of the extract (50, 100, 150 ppm) could effectively eradicate Trichodina nigra after 180 min of treatment (53.03 %-85.35 %). The extract showed no acute toxicity to whitespotted freshwater catfish after bath treatment up to 1,600 ppm for 15 min. The trichodinosis model was established via infection of Trichodina nigra in whitespotted freshwater catfish and bath treatment with EtMA (800, 900, 1,000 ppm) not only decreased the infection rate of T. nigra (20.00 %-46.67 %) but also enhanced the survival rate of T. nigra infected fishes (56.67 %-90.00 %) as compared to untreated fishes. The hematological (red blood cells, white blood cells, and hemoglobin) and biochemical parameters (total protein, blood urea nitrogen, creatinine, and total bilirubin) of all doses of EtMA-treated fishes were improved as compared to those of untreated fishes. These findings suggest that EtMA has potential use as a green and natural treatment to control trichodinosis in whitespotted freshwater catfish farming.
