Iranian Journal of Ichthyology
Volume:10 Issue: 2, Jun 2023

The present research was undertaken with the aim of investigating the effects of dietary supplementation with Persian shallot (Allium hirtifolium) essence in the diet on the growth, intestinal microbiota, biometric indexes, and immune response in Labeotropheus fuellebornijuveniles. For this purpose, four experimental diets containing 0, 0.10, 0.15, and 0.20 mL kg-1of the essence were prepared and the effects of each of those diets were examined with completely randomized designs over the course of 60 days. The addition of A. hirtifoliumto the diets of the fish was not found to have an impact on growth parameters. Furthermore, no significant differences were observed in the gastrosomatic indexvalues with different treatments (P>0.05). The hepatosomatic index was highest with the 0.20mL kg-1A. hirtifolium-supplemented diet (P<0.05). Survival was increased with 0.20mL kg-1A.hirtifoliumtreatment in comparison to the control fish (P<0.05). A. hirtifoliumessence did not affect the total aerobic bacteria (P>0.05), but the enteric gram-negative bacteria and lactic acid bacteria counts were found to be decreased in the experimental treatments with statistical significance (P<0.05). Values obtained for alternative complement haemolytic activity levels, lysozyme activity levels, total immunoglobulin, and dissolved protein in the skin mucus among fish that received essence were found to be higher in comparison to the control group (P<0.05), while no change was recorded for alkaline phosphatase, aspartate aminotransferase, or alanine aminotraansferase liver enzyme activities (P>0.05).Results revealed that, Allium hirtifoliumessence is suggested to obtain survival rate, skin mucus immunity and intestinal microbiota. The maximum level to add to the feed of juvenileL. fuellebornican be recommended as 0.15-0.20mL kg-1.

Pollution of aquatic environment due to different heavy metals has become a global concern, raising health-related issues for humans, as well as aquatic floraand fauna.Many agricultural and industrial effluents are directly discharged into the rivers without any treatment. They deposit heavy metals in the sediments, water, and aquatic organisms. Keeping thisenvironmental contextin mind, the main goal ofthis study was to scrutinizethe level of aluminium (Al)in water, sediments, and three fish species (Labeo rohita, Hypophthalmichthys molitrix,and Oreochromis niloticus). These samples werecollected monthly from Sulemanki Headworks, River Sutlej, Punjab, Pakistan, from January to Marchin the year2019. Water andsediment samples were collected from substations (upstream and downstream). Results demonstrated that the highest aluminium concentration was observedin upstream water and sediment samples (223.83±3.45mg·L-1and 417.25±3.59μg·g-1)than in downstream samples (222.87±3.44mg·L-1and 416.31±3.65μg·g-1).Among all fish organs, the liver had the highest accumulation of Al compared to muscle and gills. The order of accumulation in Labeo rohitawas liver > gills > muscle, in Hypophthalmichthys molitrix theorder was liver > gills > muscle, and in the Oreochromis niloticus, the order was liver > muscle > gills.This study suggests that River Sutlej should be properly monitored to safeguard water quality and protect aquatic life, ensuring the river's long-term health.

This study examinedthe concentrations of heavy metals (cadmium, zinc, lead, and mercury) and their potential health risks for consumers in the muscle and gill tissues of Capoeta fusca, collected from Lar wetland inSistan and Baluchestan province. Thirty samples were collected and heavy metal levels in samples were analyzed by ICP-OES atomic absorption spectrophotometer (Perkin Elmer, Model; Optima DV 2000). Mercury content was measured by Atomic Adsorption method (nova 400P, analytic jena) hydride production technique. The concentration of cadmium was lower than the detection limit (0/05 mg/kg) of the atomic absorption spectrophotometer, so its concentration was not reported in the study. The results showed that the amount of Lead in gill tissue is significantly higher than that of muscle tissue, and the concentration of zinc in muscle tissue is higher than that of gill. The mercury concentrations of muscle and gill tissues are not significantly different from each other. The accumulation of heavy metals in the samples follows this pattern: zinc>lead>mercury. The concentration of lead in the muscle of C. fusca is higher than the international standards. Therefore, among the investigated metals, the main risk for human health can be related to the amount of lead in fish samples, which can be transmitted to humans directly after consuming fish. The relatively high concentration of heavy metals in the studied fish is probably due to the entry of the wastewater of Zahedan city into the Lar lagoon.

Diet composition and feeding strategies of two native and non-native trout species i.e. the brown trout(Salmo trutta) and rainbow trout (Oncorhynchusmykiss)were investigated from autumn 2018 until summer 2019 in the uppermost of Emamzadeh Ali Lake (Haraz River, North of Iran). A total of 79 individuals including 59 brown trouts and 20 rainbow trouts were caught and studied. Digestive contents of feeding indices including CV (coefficient of vacuity), RLG (relative length of gut) and IF (intensity of feeding) revealed that both trout species were voracious carnivores, and showed a desirable nutritional status at all sampling seasons. Rainbow trout had a wider niche breadth than the brown trout in autumn, winter, and summer, except for spring. Feeding niche of the both trouts was highly overlapped in autumn and winter i.e. feedingon the same common resources. Percentage of overlap of both trouts was the most in autumn and winter and similar with the results of Morisita′s overlap index.

The climate system is changing at an unprecedented rate in the world. Climate change is having significant impacts on freshwater ecosystems and the fish species that inhabit them. The main purpose of this studywas forecasting the distribution of northern pike, Esoxluciusin the Caspian Sea basin under two optimistic (RCP 2.6) and pessimistic (RCP 8.5) scenarios of 2050 and 2080 by the MaxEnt model in R software. Five environmental variables including, annual mean temperature, temperature annual range, annual precipitation, flow accumulation, and slope were used for the modeling.The obtained results demonstrated that the performance of the model in predicting species distribution was "excellent"(0.977) based on the AUC (Area Under the Curve) criterion.Moreover, the results indicate that the distribution range of northern pike is likely to be reduced by 2050 and 2080 under the both optimistic and pessimistic climate change scenarios. In conclusion, the decreasing distribution of this fish, which is a commercially important and interesting species in sport fishing, poses a serious threat to food security and livelihoods. Therefore, policy makers should pay more attention to conservation and stock management of this species in the future.

This research looked at the basic information aboutThunnus albacaresfound in the northern part of Oman's Sea, and give useful information on how correctly manage of this resource. During the years of this study)1992and 2022(, over 6000fish were measured and the average length (range) of Yellowfin tuna fish in 1992and 2022was 93±26 (21-157) cm and77±18 (24-175) cm, respectively.The average weight (range) of this species was 9127±1251 (3500-55000) grams in 1992 and 10639±1450 (1100-85000) grams in 2022. The relationship between fork length and total body weight for the year 1992, W=0.014×L2.51(R2=0.83, N=750) and the year 2022, W=0.019×L2.46(R2=0.89, N=703) was obtained.Vonbertalanffy equation for this species in the northern waters of the Oman Sea (Iran)was calculated in 1992 and 2022 respectively as: Lt= 182 (1-exp (-0.39 (t +0.25)) and Lt= 177(1-exp (-0.55 (t +0.18))). The ratio of spawning potential based on length (LBSPR) in 1992 and 2022 were 0.22 (0.20-0.25) and 0.10 (0.09-0.12), respectively. Based on ratio of Pmega< 0.1, Lmean/ Lopt<1andLmean/LF=M<1show considered undesirable. Decrease of the average length, LBSPR index and increase of fishing and total mortality can be a reason for overfishing. The present study showed that the Yellowfin tuna stock has reached 'overfished' status. The findings of this study can assist management and sustainable harvestof this species stocks.