BACKGROUND: Herbal immunostimulants have numerous potential benefits in comparison to vaccines and drugs like antibiotics in aquaculture. OBJECTIVES: In this study, effects of administration of Echinacea purpurea in oral and intra peritoneal routs on some hematological and immunological parameters of the grass carp (Ctenopharyngodon idella) were investigated. METHODS: A total of 240 healthy juvenile grass carp were randomly divided into four equal groups in triplicates. Group 1 received 400 mg/kg b.w. Echinacea in intra peritoneal injection. Group 2  received 0.5% Echinacea in their daily food. Group 3 and 4 were considered as injection control and oral control, respectively. Fish were bled on day 0, 10, 20, 30 and 40 of study. Sera samples were assayed for immunological parameters: lysozyme activity, serum bactericidal activity, complement activity and NBT reduction assay. Blood samples were also used for hematological parameters: (PCV, Hb, RBC, WBC and Leukocyte differentiated count). RESULTS: Results showed that serum lysozyme and bactericidal activity as well as complement and NBT reduction activity were significantly higher in i.p. treatment than the control group (p<0.05), while in oral treatment bactericidal and NBT reduction activity increased significantly on days 30 and 40 (p<0.05). Hematological assay shows no significant differences in PCV, Hb and RBC values at each sampling period in oral and injection compared to controls (p>0.05) but WBC count and  rate of heterophils showed an increase in injection treatment group compared with the control (p<0.05). Mortality rate after challenged with A. hydrophila decreased in Echinacea treated treatments. CONCLUSIONS: This study indicates that administration of E. purperea stimulates some nonspecific immune responses in grass carp and therefore it can be recommended as an herbal immunostimulant in fish.

The purpose of this study was to determine the microbiological quality of food fish and its safety for consumers. The study included 24 fish representing grass carp, bighead carp, Siberian sturgeon, and wels catfish. Specimens were collected in winter. Aerobic bacteria, psychrophilic, Enterobacteriaceae, Staphylococcus spp., and E. coli counts were made, and the presence of Salmonella spp., L. monocytogenes, S. aureus, and other coagulase-positive staphylococci was investigated. The microbiological analysis showed a similar level of aerobic, psychrophilic, and Staphylococcus spp. contamination of the four fish species. The Enterobacteriaceae count was higher in the muscles of grass carp and bighead carp than S. sturgeon and wels catfish. No pathogenic bacteria such as Salmonella spp., E. coli, L. monocytogenes, Staphylococcus aureus, or other coagulase positive staphylococci were found in samples of the examined fish species. The fresh fish examined in this study were of good microbiological quality and there was no health risk for consumers.