فصلنامه تغذیه آبزیان
سال نهم شماره 2 (پیاپی 24، تابستان 1402)

The present study was designed and conducted to investigate the effects of varying levels of choline chloride on the microbial flora of the rainbow trout, Oncorhynchus mykiss fry. A total of 750 fish were fed with diets containing 0 (control), 250 (Cho250), 500 (Cho500), 1000 (Cho1000), and 2000 (Cho2000) mg of choline chloride per kg of feed for 90 days. The required feed was obtained from the 21 Bayza Company. The amount of microbial flora and final weight was significantly higher in the Cho1000 and Cho2000 than in the control group. The addition of choline to the diet effectively improved the microbial flora. The most suitable amount of choline chloride was between 1000 and 2000 mg/kg in the diet of rainbow trout.

Species diversity of macrobenthos in Fusheh River, in Guilan Province, North Iran was studied and biological indices developed based on macroinvertebrates were used to evaluate the health status of the river. Macrobenthos sampling in the river was carried out at 4 stations on a monthly basis beginning from May to December 2016 using a Sorber sampler (mesh size of 300 μm and surface area of 900 cm2) with three repetitions. The sampled macrobenthos were preserved in 96% ethanol and transported to the laboratory for identification. A total of 4928 individuals from two phyla of Arthropoda and Annelida, three classes of insects (Insecta), crustaceans (Crustacea) and Clitellata as well as 8 orders (including Ephemeroptera, Trichoptera, Plecoptera, Diptera, Coleoptera and Haplotaxida) along with 25 families and 31 genera were identified. The most abundant genera were Simulium sp. (35.84-46.65%), Hydropsychae sp. (15.79-33.36%) and Baetis sp. (7.87-17.66%). Parameters of total abundance, EPT richness, EPT percentage and EPT/CHIR ratio were also calculated. The EPT richness showed a significant difference in monthly samplings (p<0.05). The presence of species sensitive to pollution such as Perla sp., Isoperla sp., Chloroperla sp., Oligoneuriella sp., Heptagenia sp., Rithrogena sp., Epeorus sp., Rhyacophila sp. and Philorus sp. belonging to orders Trichoptera, Plecoptera and Ephemeroptera exhibits both the good quality of river water and the desirability of species and genera as natural food for the river fish species.

The purpose of this study was to produce a dry product from the whole common Kilka, Clupeonella caspia and to investigate the effect of drying on the nutritional value, microbial, chemical and organoleptic alterations during the storage time. The treatments included drying Kilka by two traditional and industrial methods and keeping in the ambient condition for 75 days. Staphylococcus, Coliform, Escherichia coli, and Salmonella were not observed in the experimental treatments. Mold and yeast were observed in the traditional and industrial treatments after 45 and 60 days, respectively. Salt absorption in the treatments was 24%. The total bacterial count (6.45-6.72 log CFU/g) was lower in the industrial treatment compared to the traditional one. Protein (43.28-43.7%) and fat (11-11.7%) were higher in the industrial treatment compared to traditional method. However, ash (10.30-11.7%) and moisture (18.50-27.40%) were higher in traditional treatment compared to industrial one. The sensory characteristics were evaluated better in the industrial treatment compared to the traditional treatment, exhibiting a significant difference during the storage time (p<0.05). TVB-N (industrial: 12.48-29.50; traditional: 12.61-29.36 mg/100g), PV (traditional: 0.09-5; industrial: 0.06-4.75 meq/kg oil), and TBARS in industrial treatment (0.02-0.99) had better quality (p<0.05) compared to traditional one (0.03-0.97 mg/kg). The industrial and traditional treatments displayed favorable microbial, chemical, and sensory characteristics in the ambient condition for 60 and 45 days, respectively.

This study was conducted to investigate the physiological performance of Caspian roach, Rutilus caspicus juveniles when directly released into the Caspian Sea, taking into account the possibility of their limited access to food for a period of two weeks. A total of 540 fish were randomly placed in tanks in the form of 6 experimental treatments (each with 3 repetitions) including: Group 1: Abrupt salinity increase and feeding throughout the experimental period (Ab.F); Group 2: Abrupt salinity increase and starvation (Ab.S); Group 3: Gradual salinity increase and feeding (Gr.F); Group 4: Gradual salinity increase and starvation (Gr.S); Group 5: Maintained in freshwater (control treatment) and feeding (C.F); and Group 6: Maintained in freshwater (control treatment) and starvation (C.S). The mortality rate of the juveniles and physicochemical parameters of the water were recorded daily throughout the entire experimental period. Osmolality, sodium, potassium, chloride, total protein, cholesterol, triglycerides, glucose, and liver enzymes (ALP, ALT, and AST) were measured in the fish after 14 days. Based on the obtained results, the levels of protein, cholesterol, and triglycerides in the fed fish did not exhibit significant alterations during the transfer to brackish water. However, two-week food deprivation led to a decrease in their levels. On the other hand, the increase in osmolality and sodium, chloride, and potassium in Caspian roach juveniles were only affected by the salinity increase and had no effect on their levels due to food deprivation. Therefore, the Caspian Sea bream (1-2 g) have the ability to adapt to the brackish water of the Caspian Sea and are easily resistant to the conditions of lack of access to suitable food in the new aquatic environment for two weeks.

In this study, the effect of different levels of Bio-Aqua probiotic supplement on the qualitative indices of grass carp, Ctenopharyngodon idella, as well as non-biological and biological parameters of earthen ponds was investigated. For this purpose, fish with an average initial weight of 2.0 ± 0.1 g were selected for 120 days. In the present study, treatments including 0 g/ha (control), 250 g/ha (treatment 1 = T1), 350 g/ha (treatment 2 = T2) and 450 g/ha (treatment 3 = T3) of this Bio-Aqua probiotic supplement were added to the ponds. Based on the results, the specific growth rate, daily growth rate, weight gain, and survival rate in T3 (450 g/ha) showed a significant difference compared to other treatments (p<0.05). Moreover, significant differences were found in the crude protein and moisture content of grass carp in T3 compared to the other treatments, especially the control group (p<0.05). In addition, there was a significant difference in lymphocytes, neutrophils, monocytes, hemoglobin, hematocrit, white and red blood cells count in T3 compared to the other treatments (p<0.05). Bio-Aqua probiotic supplement from 450 g Bio-Aqua /ha (in T3) caused a significant reduction in TSS, BOD, COD, nitrite, and phosphate levels of water compared to the other experimental treatments (p<0.05). In conclusion, Bio-Aqua probiotic supplementation, especially at T3 (450 g/ha) exhibited improved growth performance, nutritional value, survival rate, chemical composition, and hematological parameters in grass carp.

The zebra fish, Danio rerio is an ornamental freshwater fish. It is important because of beautiful appearance, economic value and has emerged as a pre-eminent vertebrate model for studying genetics. The use of appropriate diets is one of the most important biological components for growth and health fish. Since, protein and lipid are the main components of diet, in this feeding trial, we compared the effects of 9 diets with 3 protein levels (25, 30 and 35%) and 3 lipid levels (4, 8 and 12%) to evaluate the protein and lipid ratio on skin mucus immune indices of zebra fish. A total of 135 pieces of fish were divided into five groups with an average biomass (± SD) of 1.23 ± 0.02 g and a sex ratio of 2 to 3 (male / female) were randomly distributed into 27 aquaria (20-L) and fed 3 times daily during 4 months. Results showed that activity of lysozyme, alkaline phosphatase enzymes and soluble protein of zebra fish were  significantly higher in the fish fed 35% protein and 12% lipid (p<0.05). In conclusion, protein and lipid have a positive effect on skin mucus immune indices in zebra fish.