نشریه پژوهش های ماهی شناسی کاربردی
سال سیزدهم شماره 2 (تابستان 1404)

Alburnoides nicolausi is an endemic Cyprinidae of Iran and little is known about its biology. This study was carried out to evaluated growth pattern of this species with 636 fish samples that obtained from March up to September 2015 with beach line net. Sex ratio of male to female was 1: 1.15 that showed significant difference between sex ration of male to female in population (X2 = 3.327, p > 0.05). Maximum total length and weight were 87 mm and 13.09 g for females, 79 mm 7.75 g for males. The weight - length relation of female was W = 0.013 TL3.13 (r2 = 0.96) and the weight- length relation of male was W = 0.016 TL3(r2 = 0.96) and the total relation was W = 0.009 TL3.07 (r2 = 0.96). The results showed positive allometric growth for Female (t-test, tmale= 4.02, tfemale = 6.93, tpopulation= 3.33, p < 0.05).

This research was conducted with the aim of determining the food indices and dominant prey of Iranian sturgeon (Acipenser persicus) released fingerling fish in the estuary of the Tajan River in 2022. Sampling was carried out using a beach seine with a mesh size of 5 millimeters. A total of 46 fingerling of A. persicus were caught. The captured fingerling had an average length (TL) of 5.82 ± 0.91 cm and an average weight of 4.31±0.71 gr. Identified food items included phytoplankton, zooplankton, and zoobenthos groups. There was a significant difference in diet items within the gastrointestinal contents (p<0.05). The feeding intensity index (GaSI) averaged 25.13±13.7, with a minimum of 3.3 and a maximum of 50.1, indicating a significant correlation between feeding intensity and TL (p<0.05). The occurrence frequency index (FI) showed that copepod branch was the main food source, with a prevalence of 50.1%, and Cladocera with 33.3% was a secondary food in the gastrointestinal contents. Other organisms, including phytoplankton and zoobenthos, were rare food items. The Vacuity index (VI) indicated that juvenile fish are continuously active at this life stage, thus their intestines were not empty. The similarity percentage of food items revealed that the groups Cladocera and Copepoda had the highest similarity at 79.6%, followed by Chironomus and Rotifera at 80.8%. Other food items ranked below. The important food index (ISI) showed that Copepoda was identified as an important food source, accounting for 46.8% in the gastrointestinal contents. In conclusion, Persian sturgeon (A. persicus) fingerling at this age has a planktivorous and feed mostly on zooplankton.

This study aimed to estimate the growth and mortality parameters of the bigeye shad (Ilisha megaloptera) in the northeastern Persian Gulf (Hormozgan Province). A total of 367 specimens were seasonally collected using coastal set nets (mashata), shrimp trawl nets, and encircling gillnets from April 2019 to March 2022. The highest frequency for both sexes was observed within the 11–14 cm length class. The length–weight relationships were estimated as W=0.0084L3.034 for femalesW=0.0116L2.87 for males, and WW=0.0095L2.94 for the total population. Length distribution between sexes differed significantly. Based on otolith readings and the Gulland–Holt method, asymptotic length (L∞) and growth coefficient (K) were estimated at 26.48 cm and 0.53 yr⁻¹ for females, 20.13 cm and 0.79 yr⁻¹ for males, and 25.69 cm and 0.58 yr⁻¹ for the total population. Total mortality (Z) was calculated at 1.76 yr⁻¹ for males, 1.33 yr⁻¹ for females, and 1.55 yr⁻¹ for the total population. The results indicate a relatively balanced sex ratio and length distribution, but notable differences in growth parameters between sexes. The estimated growth and mortality rates suggest a short life cycle and rapid growth, particularly in males.

The study of population structure in aquatic species using a geometric morphometric approach has gained increasing importance for understanding phenotypic patterns and providing sustainable management strategies. In this study, the population structure of Chacunda gizzard shad (Anodontostoma chacunda) was examined across four coastal stations in Hormozgan Province (Bandar Abbas, Qeshm, Bandar Khamir, and Jask) using geometric morphometric methods. A total of 240 specimens were collected during June and July 2024, and 10 anatomical landmarks were marked on the left lateral side of each fish using TpsDig2 software. Data analysis employing Procrustes analysis, principal component analysis (PCA), and discriminant function analysis (DFA) revealed significant differences between temporal and spatial sampling stations. The results indicated a marked morphological separation between populations across the two sampling months, with phenotypic variation patterns in June primarily focused on caudal landmarks and in July on head and dorsal fin landmarks. These findings suggest that A. chacunda's body structure is highly sensitive to environmental and seasonal changes and may reflect phenotypic adaptations related to the species’ migratory and feeding behaviors or pressures from human activities. Considering the ecological and economic significance of this species in southern Iran's ecosystems, the results of this study provide valuable baseline information for stock management and the designation of conservation units.

This study aimed to investigate the protective effects of synbiotic (Basibus subtilis and inulin) in the diet on the physiological performance of Nile tilapia (Oreochromis niloticus) against oxidative stress caused by salinity stress. The experiment was conducted in two stages; in the first stage, fish were placed in 12 tanks (4 treatments, each with 3 replicates) and fed with different levels of synbiotic (mixture of 2.5 × 1011 cfu/g of probiotic Bacillus subtilis and 2.5, 5 and 10 g of prebiotic inulin) for 8 weeks in treatments (S1S, S2S and S3S) and a control treatment without synbiotic (S0S), respectively. In the second stage, all fish fed with different levels of synbiotic were subjected to salinity stress at a concentration of 15 g/L for 21 days. Blood plasma samples of tilapia were collected at the end of salinity stress to measure immune factors, stress indices and antioxidant capacity. The results showed that the plasma lysozyme and complement activities were significantly higher in the S3S and S2S treatments than S0S. Total immunoglobulin significantly increased in the S3S treatment (27.37 ± 1.45 mg/ml) compared to the control treatment (19.52 ± 1.15 mg/ml). Stress indices (cortisol, glucose, AST and ALT) increased significantly in the control treatment compared to other experimental treatments. After salinity stress, plasma superoxide dismutase (SOD) increased, while plasma malondialdehyde (MDA) decreased significantly in S3S treatment. Catalase enzyme concentration did not differ between experimental treatments. Based on the results obtained, the synbiotic was able to show protective effects against salinity stress, therefore, the use of a mixture of 2.5 × 1011 cfu/g of Bacillus subtilis and 5 and 10 g of inulin (S2S and S3S) is recommended for Nile tilapia.

The heart in fish is the first organ to start working. The heart of fish has four parts and plays an important role in supporting high metabolic activity and adapting to environmental changes at different stages of fish development. Histologically, the atria and ventricles of fish have trabeculated muscles, and the muscle density in these two parts is different.

In this study, 10 of adult barbus grypus weighting 443.5±30.5 grams . After performing histological procedures, the muscle thickness and the number of muscle nuclei in the two parts of the atrium and ventricle were compared.

The results of this study showed that the number of nuclei in cardiac muscles is greater than in the ventricles, and on the other hand, the thickness of the ventricular muscles was also greater. It was also shown that the cardiac muscles of this type of fish are striated and dense, with reduced muscle density in the atria, red blood cells were seen in tissue sections with oval nuclei, and muscle nuclei were also very pale and spindle-shaped.

Given that the histology and anatomy of the heart are different in different fish, and on the other hand, structural differences cause fish to adapt to different environments, and the heart also plays an important role in supporting high metabolic activity and adapting to environmental changes at different stages of fish development, histological information in different species is very valuable.