Antifungal effects of Achillea officinolis and Matricaria chamomilla plant extracts on control infection of rainbow trout eggs by Saprolegnia parasitica

One of the important factors causing the loss of fish eggs in the hatcheries is contamination with Saprolegnia parasitica. Today, Green Malachite is the most widely used drug against this fungi, which has been confirmed to be carcinogenic. The aim of this study is to investigate the antifungal effects of Matricaria chamomilla and Achillea officinolis extracts to control of infected rainbow trout eggs with Saprolegnia parasitica in comparison with Green Malachite. In this study minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were mesured by Micro Broth Dilution test and the growth of fungi in a solid medium, and determined as 100 and 150 mg/mL for M. chamomilla and 150 and 200 mg/mL for A. officinolis, respectively. The eggs of rainbow trout were divided into four treatments (control, two plant extract and Green Malachite treatments) and were exposed with MFC of each extract and 1 mg/L Green Malachite for 1 hour/day during incubation period. The mortality of eggs were compared in stages of fertilization to sighting, sighting to hatching and total incubation period. The results showed that the mortality of eggs in each stage in Green Malachite treatment was significantly lower than control and A. officinolis (p˂0.05), but did not show difference with M. chamomilla treatment (p>0.05). The lack of significance difference of mortality and hatching percentage in M. chamomilla (75.90±0.26%) compared to Green Malachite (77.97±2.32%) showed that M. chamomilla extract with antifungal effects is a suitable natural remedy for replacing Green Malachite in fish eggs hatcheries.