The effect of preliminary ascorbic and citric acid (AA and CA, respectively) soaking treatments on the rancidity development in Wels catfish (Silurus glanis) fillets during further frozen storage ()18°C; up to 6 months) was studied. Rancidity development was measured by biochemical quality indices (formation of free fatty acids, peroxides and secondary oxidation products) and compared with sensory analysis (appearance, rancid odour and consistency) and general chemical analyses (pH, expressible moisture and heme iron contents). When compared with control samples, AA-and CA-treated samples showed a lower (P < 0.05) formation of primary and secondary lipid oxidation compounds that was corroborated by a longer (P < 0.05) shelf-life time as a result of a lower rancid odour formation. According to these results, control samples showed a higher (P < 0.05) heme iron breakdown (months 3-6) and a lower (P < 0.05) water-holding capacity (higher expressible moisture value) (month 6).

This study involved 120 pike, Esox lucius, captured from Anzali wetland. Parasite fauna were identified in captured fish. Also, changes of haematological parameters were compared both infected and uninfected fish. Parasitological inspections revealed the following infestations: Skin: Lernea cyprinacea, Argulus foliaceus (Crustacean) and Tricodina sp. (Ciliatea). Gill: Dactylogyrus sp. (Digenea) and Tetraonchus monenteron (Monogenea). Eye: Diplostomum spathaceum (Digenea). Gut: Eustrongylides exises, Rhipdocotyle illense, Raphidascaris acus (Nematode), Corynosoma Strumosum (Acanthocephala). Most prevalence and intensity were related to Eustrongylides exises and Rhipdocotyle illense. Following haematological parameters were evaluated: haematocrit, haemoglobin concentration, erythrocyte and leukocyte counts, mean cell volume (MCV), mean cell haemoglobin, mean cell haemoglobin concentration lymphocytes, monocytes and eosinophils. Significant difference was found for MCV between infected and uninfected fish.

A parasitological investigation was done on 175 specimens. Infections of A. brama orientalis were analyzed according to the age and sex. The fish also were examined for evaluation changes of haematological parameters in relation to parasitic infection. Four parasites were found, including-Caryophyllaeus laticeps and Ligula intestinalis (Cestoda), Diplostomum spathaceum (Platyhelminthes) and Trichodina sp. (Ciliophora). Among identified parasites maximum prevalence and mean intensity were related to Ligula intestinalis and Caryophyllaeus laticeps respectively. The values of prevalence and mean intensity showed significant differences among ages. Our results revealed prevalence, mean intensity and abundance had not significant difference between males and females. Parasite infection provoked reduction (P \ 0.05) in haematocrit, mean cell volume and lymphocyte. On the other hand, significant increase (P \ 0.05) in white blood cell (WBC), mean cell haemoglobin concentration and neutrophil in blood of infected fish was observed. Significant differences were detected for the WBC, lymphocyte and neutrophil (infected versus uninfected by Trichodina sp., Diplostomum spathaceum and Caryophyllaeus laticeps). In addition to WBC and lymphocytes, significant change was observed for the haemoglobin (Hb) (infected versus uninfected by Ligula intestinalis).