Pathogenicity and control of Aeromonas hydrophila and A. veronii in Indian major carps (Catla-catla) by the effect of herbal supplement of Andrographis paniculata (Lamiales: Acanthaceae)

Abstract

Plant extracts are focused for their potential as immunostimulants against the infectious diseases of fish. The present study was designed to evaluate the acquired immunity stimulated by methanolic extract of Andrographis paniculata against the pathogens, Aeromonas hydrophila and A. veronii in Catla-catla. The fishes were fed with diet incorporated with A. paniculata extract. Post 14 days, serum parameter analyses revealed an increase in total haemoglobin (10-11.5 g %), erythrocyte (34.7 105 mm-3) and leukocyte count (3.9 × 104 cell.mm-3). The phagocytic index of infected fishes treated with extracts increased in a dose dependent manner (31.25%), exhibiting 100 % Relative Percentage Survival. Adverse changes in the disease symptoms were also observed post treatment with extracts. The extracts of A. paniculata were able to inhibit the pathogens even at low concentration (50 µl). This study hence proves that the extracts of A. paniculata can be used as an immunostimulants.