parameters of fish were examined after 30, 60 and 90 days of feeding. Fish
were challenged with A. hydrophila 90 days post-feeding and mortalities were recorded over 10 days
post-infection. The results demonstrate that fish fed with Euglena showed increased levels of superoxide anion production, lysozyme, serum bactericidal activity, serum protein and albumin (P < 0.05 compared
with the control group. Following challenge with A. hydrophila less survivability was observed in the
control group (56.65%) than the group fed the experimental diets. The group fed 0.5 g Euglena kg1 dry
diet showed the highest percentage survival (75%). These results indicate that Euglena stimulates the
immunity and makes L. rohita more resistant to A. hydrophila infection.