Abstract:
Parasitic infection is considered one of the major constraints in commercial fish farms owing to
huge economic losses. Although there are plenty of commercial drugs available for treatments,
those synthetic chemicals are more hazardous to the host and the environment than the parasite.
Therefore, a special trend can be seen towards herbal medications. The present study is utmost
significance as it focused on a well-known spice, Garlic (Allium sativum) as a bath treatment
against gyrodactylosis caused by Gyrodactylus sp. The soxhlet extraction method was used to haul
out the water-soluble compounds and the major components were identified using Thin-Layer
Chromatography (TLC) techniques. During the phytochemical analysis, flavonoids, glycosides,
quinones, and diterpenes were identified where the alkaloids, tannins, and phenols were absent in
garlic extract. To find out the LC50, values acute toxicity test was performed in 72 hours with
triplicates and 802.2ppm value was resulted. 216 of infected adult guppies (2.9 ± 0.1cm, 0.32 ± 0.05
g) were used for a three-hour in vitro bath treatment with different concentrations of garlic extract
including 50, 100, 150, 200, and 250 mg/L. Complete recovery from gyrodactylosis is observed by
the means of microscopic observations at 3, 2.5, 2, and 1.5 h with 50, 100, 150, and 200mg/L of
concentrations, respectively. According to the observations, it can be concluded that exposure to
garlic extract caused the parasite to first detach from the host, then restrict its movements, and
finally die. A significant negative correlation (p<0.01) can be observed between the garlic
concentration and the eradication time. 250 ppm garlic extract bath for 0.5 hours was identified as
the optimal and most effective treatment against gyrodactylosis. Therefore, garlic extract can be
suggested as a herbal bath treatment against agent Gyrodactylosis infection in guppy fish.
