Use of Onion (Allium cepa) and Garlic (Allium sativum) Wastes for the Prevention of Fungal Disease (Saprolegnia parasitica) on Eggs of Rainbow Trout (Oncorhynchus mykiss).

This study was designed to prevent fungal disease (Saprolegnia parasitica) that occurs on rainbow trout eggs (Oncorhynchus mykiss) by using wastes of onion (Allium cepa) and garlic (Allium sativum) plants. For this purpose, fertilized rainbow trout eggs were exposed to garlic skin, garlic stem and onion skin aqueous methanolic extracts by bathing in concentrations of 0.4, 0.8, 1.6 and 3.2 g/L, whereas the control group was left untreated. The larvae in all groups were monitored until they become free-swimming larvae, the number of eggs died due to fungus was recorded, and the data obtained from experimental groups and control group were compared. As a result, it was determined that onion skin had no effect on the number of eggs that died due to fungus (p > .05), while garlic skin and garlic stem extracts significantly reduced the number of fungal infestations without affecting the number of live larvae or the embryological development of the eggs (p < .05). In light of these data, we conclude that garlic skin (0.4, 0.8, and 1.6 g/L) and garlic stem (0.8 and 1.6 g/L) aqueous methanolic extracts are effective at preventing Saprolegnia parasitica infestation on rainbow trout eggs and may be used in aquaculture.