The influence of chitosan on immune status and survival rate of Cyprinus carpioL. challenged with Aeromonas hydrophila

Abstract

The aim of our study was to evalute the effect of chitosan on non- specific immunity and survival rate of Cyprinus carpio challenged with Aeromonas hydrophila. A total of 80  common carp  (36.4 ± 0.73 g) were devided into four dietary groups: The first group (G1) was served as control fed on chitosn-free diet, the second group (G2) was fed on diet supplemented with 0.75% chitosan, the third group (G3) was fed on diet supplemented with 1.5% chitosan and the fourth group (G4) was fed on diet supplemented with 2% chitosan for 45 days. After 45 day of feeding trail, 6 fish per treatment were sampled for immunity determination (respirotary burst activity, bacteriocidal actvity and lysozyme arctivity). 36 fish in all treatment groups were challenged intramusculary with Aeromonas hydrophila on day 45. The results indicated that the fish fed on diet containing 2% chitosan (G4) had the significant increased (P<0.05) in respirotary burst activity, bacteriocidal actvity and lysozyme arctivity compared to control group and to other treatment groups, followed by G3 and G2 respectively. Also, G4 showed highest resistance to challenged A. hydrophila compared to other groups.  Control group (G1) showed the decreased performance in all non sepecific immune parameters and simultaneously increased in mortality rate. Therefore, these results indicate that 2% chitosan as addititive fed  could be used as prophylactic in common carp culture to enhance the protection against any possible infection by A. hydrophila which is useful for practical fish culture.