نشریه علوم آبزی پروری ایران
سال یازدهم شماره 2 (پیاپی 20، پاییز و زمستان 1402)

This study aimed to investigate the effect of frying silver carp sausage using different vegetable oils on the composition of fatty acids and the nutritional quality of its fat. First, silver carp surimi was prepared by washing method, and then sausage was prepared with other food items and additives. Then, the sausages were fried into four vegetable oils (olive, rapeseed, soybean, and sunflower oils) by immersion in oil (at a temperature of 180±3 ℃). The results showed that the type of frying oil significantly affects the fatty acid composition and nutritional quality of its fat (P≥0.05). Sausages fried with olive and sunflower oil had the highest (28.7) and the lowest (13.9) saturated fatty acids (in percentage), respectively. The same trend prevailed regarding the monounsaturated fatty acids. However, regarding polyunsaturated fatty acids, the results were the opposite i.e. the highest and lowest amounts were observed in sausages fried in sunflower and olive oil, respectively. Although in terms of total omega-3 fatty acids, fried sausages in sunflower oil had the highest value among other experimental treatments, but in terms of the ratio of omega-3 fatty acids to omega-6 (n3/ n6), the highest value was observed for fried sausages in rapeseed oil. The results of the present study showed that although sausages cooked with different vegetable oils contain most of the essential fatty acids necessary for humans (including linoleic and alpha-linolenic) because of a high proportion of omega-6, but in all experimental oils, their planned consumption is recommended.

In this study, the effect of lack and phosphorus deficiency (dipotassium phosphate; K2HPO4) on the growth rate, biomass, biochemical content, and fatty acid profile of Desmodemus sp. was investigated for 14 days. Accordingly, Desmodesmus microalgae were grown in culture media containing no phosphorus (P0), 10 (P10), 20 (P20), 30 (P30), and 40 mg/liter (P40). The P40 treatment was considered as a control group that had the amount of phosphorus required in the standard culture medium BG11. Based on the results, the highest cell density, specific growth rate, and biomass production were simultaneously recorded in the P20, P30, and P40 treatments on the 14th day of culture, which showed a significant difference from the other two groups (P<0.05). In addition, the highest chlorophyll a was also recorded in these three groups, which showed a significant increase compared to the group without phosphorus (P<0.05). The lowest chlorophyll b was recorded in P0 (1.62 mg/L) compared to other experimental groups (P<0.05). The analysis of body composition showed the highest amount of lipid productivity (14.93 mg/liter per day) in P20 treatment, which has a significant difference with other experimental groups, except for P10 (13.17 mg/liter per day) (P<0.05). The highest protein productivity rate was measured in P30 and P40 groups (P<0.05) and the highest carbohydrate productivity rate (10.55 mg/L per day) was measured in P40 without significant difference with P30 (8.87 mg/l per day). The highest amount of saturated fatty acids was observed in P0 (47.66% of total fat) and the highest long-chain unsaturated fatty acids in P40 treatment (30.58% of total fat) without significant difference with P30 (29.33% of total fat). Based on the results, the concentration of 20 mg/liter of phosphorus is a suitable concentration for the cultivation of Desmodesmus sp. microalgae for the production of biofuel, while the concentration of 40 mg/liter of phosphorus is a suitable concentration for the cultivation of the microalgae for using in the food and aquafeed industries.

The present study was performed to investigate the effect of dietary nucleotides on the growth and apparent digestibility of Sterlet sturgeon, Acipenser ruthenus. Fish with an average body weight of 95.33±1.23g and total length of 0.30±0.5 cm were divided into 5 experimental groups with 3 replications, each containing 12 fish which were randomly distributed in tanks with 500 L working capacity. The fish were fed diets containing 0.0, 1.5, 2.5, 3.5, and 5.0 g kg-1 nucleotide. The experiment was conducted in a completely random design for 10 weeks. The results showed a significant increase in the weight gain percentage of fish in treatments of 2.5, 3.5, and 5.0 g kg-1 nucleotide than those in the control treatment (P<0.05), reaching the highest percentage of 119.07±19.97% in fish fed diet supplemented with 5.0 g kg-1 nucleotide (P<0.05). However, no significant difference was recorded in the values of this variable between fish-fed diets supplemented with more than 2.5 g kg-1 nucleotide (P>0.05). There was also a significant increase in the total length of fish fed diet supplemented with 5.0 g kg-1 nucleotide (25.5±0.8 %) compared to those fed the basal diet (17.76±0.73 %) (P<0.05), while no significant difference was found with those in fish fed diet supplemented with 3.5 g kg-1 nucleotide (P>0.05). The highest apparent digestibility of dry weight was 80.32±0.47% in fish fed a diet containing 5.0 g kg-1 nucleotide, while the lowest value was 73.24±0.45% in fish fed the basal diet (P<0.05). The highest apparent digestibility of protein was 90.94±0.24% in fish-fed a diet containing 5.0 g kg-1 nucleotide, which had a significant difference with that in fish fed a diet containing less than 2.5 g kg-1 nucleotide (P<0.05). However, no significant difference was observed in lipid apparent digestibility of fish between the experimental treatments (P>0.05). In general, findings of the present research indicated that dietary supplementation of nucleotide in the diet has a significant impact on the nutrient digestibility of sterlet sturgeon, with the best response obtained when fish fed a diet containing 3.5 g kg-1 nucleotide for ten weeks.

These small loaches are distributed from the upper Tigris River basin to Pakistan. Currently a total of 16 species are recognized in Iran. Since osteology has proven to be a useful tool for studying the taxonomy and phylogeny of fishes, including loaches, we have studied some osteological characters are studied in 13 species from Iran. To conduct this study, the fishes were fixed in 10% formaldehyde, stored in 70% and then deposited in the Zoological Museum, Collection of Biology Department, Shiraz University. Digital X-ray radiographs were taken from the left side of all fish using a Faxitron Bioptics. Based on the obtained results caudal skeleton consists of five or six hypurals and unpaired epural, parahypural and pleurstyle bones. The pleurstyle is fused to the last centrum. The shape of the epural is varies in each species. The fifth hypural is triangular, not connected to the terminal centrum and different in size. The results revealed that some Paraschistura species can be distinguished based on the caudal complex, especially by the number of hypurals, dorsal- and caudal-fin rays and the number of vertebra. Therefore, it seems that specific characters, are more useful in distinguishing higher taxa such as lineages, genera and families rather than individual species.

The threats to the rivers caused by human activities and stress factors that have endangered the biodiversity of the inhabitants in these ecosystems, especially fish. Therefore, it is necessary to understand the habitat needs and assess the suitability of the habitat for organisms living in rivers to protect biodiversity. This study aimed to investigate the Habitat Suitability Index (HIS) of Barbus karunensis in Bashar River using the kernel smoothing method in summer and autumn seasons 2021. In this study, 16 stations were selected and sampled with 3 repetitions. At the same time, environmental factors, including temperature, geographical slope, water velocity, river width, water depth, elevation, pH, electrical conductivity (EC), and total dissolved solids (TDS) were recorded and measured. Based on the results, the habitat preference of this species in the summer season was river sections with high elevation, high temperature, low average water velocity, high slope and width of the river, middle depth with high pH, average TDS values, and higher EC. In the autumn, the most preferred habitat of fish was high elevation, low temperature, low water velocity, high slope, medium width, low depth TDS, and pH. It can be concluded that the habitat of B. karunensis was different in the summer and autumn seasons and this species prefers different ranges of environmental parameters in the summer and autumn seasons.