Immune Response of VNN (Viral Nervous Necrosis) Infected Grouper Utilizing Chlorella vulgaris Extract as an Anti-Virus Candidate

The quality and health of fish guarantee the success of aquaculture. However, grouper aquaculture are susceptible to diseases such as VNN (Viral Nervous Necrosis). It is necessary to determine the fish immune response system by observing the changes in the number of blood cells. Utilizing alternative substances, Chlorella vulgaris for instance, may minimize infection. This study aims to determine the effect of C. vulgaris extract treatment, as a candidate of VNN anti-virus, through hematological observations. The research method used qualitative experimental design by describing the fish immune response based on the number of blood cells. Fish blood was collected from each treated fish in the following treatments: (A) healthy fish, (B) VNN-infected fish, (C) VNN-infected fish treated with 17 µg / mL C. vulgaris extract, (D) VNN-infected fish treated with 33 µg / mL C. vulgaris extract, and (E) VNN-infected fish treated with 50 µg / mL C. vulgaris extract. The blood cells are observed using a light microscope. The water quality parameters analyzed were Temperature, pH, Salinity, and Dissolved Oxygen (DO) as supporting data. The research results showed that healthy fish has a high number of erythrocytes (28 cells/field of view). Treatment (D) shows a value close to healthy conditions, namely 22 cells/field of view. C. vulgaris extract treatment on VNN-infected groupers improves the immune system as indicated by an increased number of erythrocytes and decreased number of basophils cells (11 cells/field of view) and neutrophils (16 cells/field of view). Examination of water quality parameters shows tolerable conditions for the growth of groupers based on quality standards.