نشریه پژوهش های ماهی شناسی کاربردی
سال یازدهم شماره 1 (بهار 1402)

More than 70 millions of Kutum (Rutilus frisii) fingerlings are released in the rivers of Guilan province annually for restoring, but there is few data about biological chracteristics about the fish during staying in the rivers downstream, thus this study has been done on abundance, growth, condition factor and diet of released fingerlings of kutum fish (Rutilus frisii) in Khoshkrud River downstream, and for this propose, 3 stations selected in the river downstream and sampling has been done using electroshocker monthly from Oct. 2022 until March 2023. Results showed Alburnoides samii, Capoeta razii, Rutilus frisii, Ponticola gorlap and Cobitis with 249.2, 108.7, 85.2, 32.2 and 31.4 individuals in 100 m2 catch effort had the most abundant. The fingerlings of kutum fish present in all months in the river downstream and its density varied 20.0 to 212.5 individuals per 100 m2. Studied fingerlings (n=119) had a weight of 2.10-15.10 (5.77±2.54g, average±s.d), total length of 6.62-12.20 (8.61±1.13cm) and condition factor 0.71-0.97 (0.86±0.05) and there was significant statistical difference only in condition factor between autumn and winter. The length-weight parameters was calculated for b-value 3.09 and correlation coefficient (r2) 0.98 and indicated isometric growth patterns. It was determined vacuity index 40.9% and 59.6%, the mean relative length of intestine 0.78±0.08 and 0.75±0.08 and the mean fullness intensity 76.1±97.1 and 71.3±118 in kutum fingerlings in autumn and winter seasons, respectively. There was 6 macro-invertebrates and 14 genera of algae in gut of kutum fingerlings and in the fish intestine were abundant Chironomidae from benthos and genera Synedra, Navicula, Diatoma and Melosira from algae cells in both seasons. In general, fullness intensity, condition factor and water temperature were no suitable for staying fish fingerlings in the stuied duration, but was not distinguished the reason of settle of fish in rivers and no emigration to sea water.

In this study, some biological characteristics including sex ratio, gonadosomatic index, absolute and relative fecundity and egg diameter of H. leucisculus population in Ala-gol Wetland of Golestan province were investigated. Sampling was done in the summer of 1400 and 148 samples were caught with a net. The sex ratio of caught fish was equal to 1:1. The mean gonadosomatic index (GSI) for females was 10.72 ± 3.09 and for males it was 1.78 ± 0.70. The maximum total length and weight of females were 120 mm and 13.87 grams, respectively, and 127 mm and 13.48 grams for males. The minimum, maximum and average of absolute aggregation were calculated as 1334, 18340 and 7239.66, respectively, and for relative aggregation (eggs per kilogram of body weight) as 202, 1526 and 819.99, respectively. The average diameter of the eggs was 0.57 mm and varied from 0.46 to 0.66.

The presence- absent and frequency of any species in a riverian habitat is hnfluenced by numerous factors, and the particular domains prefer the changes of each habitat factor. The purpose of this study was to investigate the habitat suitability index of Alburnoides eichwaldii in the Lavij River in Mazandaran province. A sampling of fish was carried out at 22 stations in Junuary 2017 by electrofishing, frome the top of the river to the Chamestan city (Kashpel forest park) in downstream of the river. At each station, 11 environmental factors were measured. The results showed that, station 21 is the most suitable station for A. eichwaldii and at this station, parameters such as altitude (until 150 m), width (6-9 m), depth (19-25 cm), substrate (3-7 cm) and water flow velocity (0.6-1 m/s) played the highest role in the high habitat suitability index. According to the obtained chart of the CANOCO software, temperature and ammonium the importance and impact of these variables on the frequency of species, especially A. eichwaldii in the Lavij River. The results showed that areas like station 21, which have been less destroyed in terms of human activities, had the highest level of suitability.

In the present study, for the morphological comparison of Glyptothorax galaxias populations, 54 samples were caught from the four stations of Afsarabad, Armand, Bazoft and Beheshtabad from the headwaters of the Karun watershed. The geometric morphometric analysis was done based on 15, 13 and 10 homologous morphological landmarks on lateral, ventral and dorsal. Landmark method determined the out shape body and related analysis such as PCA, CVA, DFA, and dendogram was performed to show if there were differences among population of Glyptothorax galaxias. The results showed that the population living in Armand branch is separate from other populations, Bazoft and BeheshtAbad populations have the least distance and are placed in the same cluster, and Behesht-Abad and Afsarabad populations overlap with each other to some extent. It seems that the difference between different habitats in terms of flow intensity, river slope, nutritional conditions and water physics and chemistry is the reason for the difference in populations, which should be investigated in future studies. Considering that the species G. galaxias is native to the drainage basin of the Persian Gulf of Iran and the studies conducted on this species are very few and limited. Therefore, a comprehensive study of this species from different morphological aspects is necessary.

Although the use of indicator organisms and their different tissues is commonly used to evaluate environmental pollution, there is still a need to identify a non-lethal, reliable and sensitive indicator in aquatic environments. In this research, multivariate indices were used based on habitat accumulation conditions. For this purpose, the ratio of elements of pectoral fin spines of ozone-exposed fish were compared as a non-lethal index to evaluate the habitat of the north and south of the Caspian Sea. For this purpose, multivariate analyzes and non-normal analyzes were used in the required cases to compare the samples of North and South Caspian Sea. The ratios of W: Ca, Tl: Ca, Ta: Ca, Sn: Ca, Se: Ca, Ni: Ca, Nb: Ca were higher in the southern samples than in the northern ones, which probably reflected the difference in the availability of metal absorption compared to calcium. Despite the recorded differences in the proportion of pectoral fin spine elements of ozone-exposed fish between the north and south of the Caspian Sea, all the multivariate results also reflected this habitat differentiation. These results showed that the pectoral fin spine can be confirmed as a good non-lethal indicator due to its capacity to accumulate pollutants and also as a biological indicator, and therefore it can be used for environmental evaluations, although the importance of continuous monitoring and protective measures is suggested along with continuous evaluations.

So far, several studies have been conducted to increase aquatic production by affecting growth and reducing mortality through various feed additives, but studies on the effect of adding these additives directly to water are limited. The aim of the present study was to investigate the effect of adding Lactobacillus rhamnosus PTCC 1637 to water on hatching rate, yolk sac uptake and some growth indices during spawning to juvenile stages of rainbow trout. This study was divided into 3 parts; 1: day 1 to 7, 2: day 1 to 20 and 3: day 1 to 60, with the addition of concentrations of 106 and 107 CFU/mL into the water and also a control group. Results of the first and second parts showed that the range and duration of the hatching in all probiotic treatments were significantly different from the control and the yolk sac absorption were significantly shorter in both groups under 106 and 107 CFU/mL concentrations compare to the control (P<0.05).In the third part, the weight, length, feed conversion ratio, body weight gain percentage, specific growth rate and condition factor among probiotic treatments showed a significant difference with control (P <0.05). In all of these parameters, the best results were recorded in a treatment in which the hatched eggs were incubated from 1 to 60 days at 107 CFU/mL; The best feed conversion ratio was also recorded in the same treatment (P<0.05).Overall, increasing the duration of lactobacillus ramenosus treatment improved the performance of the hatching and growth factors in the early stages, as well as increasing the health status and growth in the later stages of fish life. Overall, the addition of bacteria to the water has improved the yield of growth and development in the early stages of life of rainbow trout and can be the easiest and most effective method.

This study aimed to investigate the effect of salt (sodium chloride) supplementation in the diet on survival, biochemical indices, and tissue histology of juvenile wild common carp under salinity stress. Fish fry (approximately 1.1 g) were fed diets containing 0%, 5%, and 10% sodium chloride for 15 days, then directly transferred to brackish water (13 g/L) and sampled after 3 and 10 days. Diet or sampling time had no significant effect on survival and body moisture of fish. Sodium, glutathione reductase, and glutathione peroxidase levels in the body significantly increased three days after salinity stress, and returned to pre-stress levels after 10 days. Body moisture levels significantly decreased after salinity stress, but potassium and chloride levels in the body increased and remained significantly higher than pre-stress levels for up to 10 days. Prior to salinity stress, glutathione levels were higher in high salt treatment groups compared to control groups, and 10 days after salt stress, glutathione levels were higher in the 10% salt treatment group compared to the other two groups. Malondialdehyde in the body was significantly lower in sodium chloride treatments than the control. No significant and important histological lesions were found in the fish gill and kidney after salinity stress. This study suggests that wild carp fry can tolerate direct transfer to the Caspian Sea brackish water, without dietary sodium chloride supplementation. Dietary 10 g/kg salt supplementation decreases lipid peroxidation in the fish.

Electric currents make changes and physiological effects on fish and affect reproductive indicators such as gamete quality, corticosteroid levels and ovarian function. In this study, 180 pieces of zebrafish were placed in 12 plastic containers, each of which contained 1.5 liters of city water, and were classified into 4 groups. Then the groups were affected by three different doses of electromagnetic waves (with intensities of 2.5, 5 and 7.5 milli Tesla) chronically (28 days). One group was also considered as a control. After the end of the exposure period, the histological examination of ovarian tissue showed that long-term exposure at the intensity of 7.5 milli Tesla has a greater effect on ovarian tissue than the intensity of 2.5 and 5 milli Tesla. So that a higher percentage of oocytes leave the normal process and enter the atresia phase. These oocytes will not have normal fertilization if released. Increasing of magnetic field intensity is associated with increasing of oocyte diameter so that the size of the oocyte reaches its highest level at the intensity of 7.5 milli Tesla. In general, the presence of magnetic waves in sea waters may affect the reproduction of marine organisms in the long term.