نشریه پژوهش های ماهی شناسی کاربردی
سال دوم شماره 3 (پاییز 1393)

The genus Capoetais considered being a complex taxa of Iranian freshwater fishes in terms of taxonomy. Among the members of this genus, comparing morphometrics and meristic characteristics of Tuini fish (Capoeta damascina) from different basins do not allow their distinction despite some differences. Hence, osteological features can be considered as an important characteristic to investigate their taxonomy. In addition, knowledge of osteological features, particularly cephalic structures, can be use in understanding their biological features, such as feeding and respiration. Therefore, this study was aimed to describe osteological characteristics of Tuini fish from Tigris basin. To do so, 20 specimens were collected from the Gheshlagh River using electro fishing. Specimens were fixed into 10 percent buffered formalin after anaesthetizing and then cleared and stained for osteological examinations. The skeletal structure of this species showed differences in form of some bony elements including jaws, quadrate, symplectic, parasphenoid, various parts of occipital region and urohyal in comparison with other cyprinids which can be considered as discernible osteological characters of this species. Regarding the weakness of morphometric and meristic traits for taxonomic study of the member of C. damascina, the findings of this research can be set as the basis for future taxonomic studies of this taxon.

This study aimed at investigating the effect of probiotic bacillus on energy utilization and ammonia and urea excretion in Onchorhynchus mykiss larvea using five blends of probiotic bacillus via supplementation of diet for 60 days. Rainbow trout larvae (avg 46332 mg) were fed with the diet supplemented with 1×106 CFU/ml (treatment Tau-1), 1×107 CFU/ml (treatment Tau-2) and 1×108 CFU/ml (treatment Tau-3), per 100g food and their effects were compared with those of control diet containing no probiotic. Feeding varied from 5% to 8% of the body weight in breeding period, though the fishes were not fed during the excretion experiment. Results revealed that ammonia and urea excretion in experimental treatments had significantly decreased in comparison to control treatment (P

This study was conducted to evaluate the effect of dietary prebiotic mannan oligosaccharide on growth performance, survival and resistance against environmental stress of rainbow trout (Oncorhynchus mykiss) larvae during a 6-week experiment. Basal starter diet (containing 50% protein, 20% lipid and 21.65 MJ/kg energy) were supplemented with 0 (control), %.0.1, %0.2, 0.3%, 0.4% and %0.5 in a totally randomized design trial in triplicate groups. After acclimation, the larvae (initial weight of 370 mg) were placed and fed into trough (250 larve per tank). At the end of the trial, growth factors, survival, nutrition and stress resistance such as high temperature (33 °C), acidity (Low pH pH=2, Hcl), alkalinity (High pH pH=12, NaOH) and high salinity (40 ppt) were assessed. Results revealed that fish fed by different levels of prebiotic mannan oligosaccharide displayed significantly higher growth performance , feed efficiency and survival rate compared to the control group and the best performance was achieved at the level of %0.3 (P

Gene expression of P450 in Juveniles of Acipenser persicus in exposure to sub lethal doses of cadmium chloride (200, 400 and 800 µg/l) were studied during 14 days. Sampling was done from the both liver and gill on days 1, 2, 7 and 14. Result showed that in gill and liver tissue, the relative mRNA- P450 expression level significantly increased in all experiment days compared to control(P

Nitrite is intermediate product in hydrogen natural cycle whose high rate of concentration level has toxic effects on fishes. In order to investigate this effect, the lethality range of this chemical was determined through initial tests. Then to determine the accurate LC50,180 piece of white fish with an average weight of 4/05 ± 0/8 g in 6 groups (5 experimental groups and one control group) were exposed to concentrations of 130, 144/5, 161/5, 180, 200 mg/l of sodium nitrite. The experiments were done based on static approach according to standard methods for 4 days (96 h). During the experiment dissolved oxygen, pH, total hardness and water temperature were measured and recorded daily. Average rate of lethality (LC50) of nitrite on white juveniles (Rutiluskutum) within 96 hours using Probit analysis was determined 146/62 mg/l. During this study, abnormal behaviors, such as unrest, swimming in the water level, and loss of equilibrium were observed. In order to observe histological changes in the liver, the tissue of torpid fish was examined at the end of each 24 h. After stabilizing the tissues in 10% formalin, 5-micron-thick tissue sections were prepared and stained using hematoxylineosin method. The most important observed liver lesions was, central venous bleeding, atrophy, hepatocyte necrosis, chronic focal necrosis, cloudy swelling and melanin and bile. The result showed that the Rutiluskutum was resistant to nitrite poison and the liver tissue can be exdamined as a biomarker of nitrite pollution index in this species.

The purpose of this study was to investigate the effect of voltage, salinity and temperature on the performance of electric fishing. To do so, 850 pcs Gambosia holbrooki from Golestan dam were hunted and transported to the laboratory. Distance from the anode, cathode and anode distance during testing were 10cm and 120cm, respectively. Experimental fish length and weight range for this species were calculated 3.818 ± 0.20 cm and 0.804 ± 0.135 gr , respectively. Electric shocks were applied to individual fish in three voltages of 15, 45 and 135 volts and 3 °c, 10 °c, 20 °c and 30 °c, and 3 salinity of 0.5, 2 and 4 g/l. Time to pass out and return to the initial state for individual fish were recorded. Statistical analysis of ANOVA, Duncan and LSD showed that the average duration of voltages and temperatures and salinities of anesthesia obtained are significantly different. The maximum and minimum anesthesia time were calculated for the Gambosia holbrooki from the salinity of 0.5, 10° c, Voltage 15, with a mean of 8.71 ± 0.74s and from the salinity of 4, 30° c, Voltage 135, with a mean of 1.44 ± 0.32s, respectively. The maximum and minimum reset time for Gambvzya were resulted from the salinity 0.5, 10° c, Voltage 135, with a mean of 94.84 ± 3.1s and the salinity of 0.5, 30° c, Voltage 15, with a mean of 20.01 ± 2.72 s, respectively.

Stripped piggy (Pomadasys stridends) is widely distributed in coastal waters of Persian Gulf. However, the reproductive characteristics of this fish were under-researched. Specimens of Pomadasys stridens were collected from the local catches at Bushehr fishery harbor from May 2010 to April 2011, by regular monthly collections. A total of 540 specimens, including 155 males and 385 females were collected and transported to Bushehr fishery research center and then to Isfahan university of technology for analysis. The total length (in millimeter) as well as the total weight (in 0.1 grams) of the fish was carefully recorded. The total length of the mature fish ranged from 12.6 cm to 23 cm (females) and 11.7 cm to 22 cm (males) and their total weight ranged from 27.4 g to 144.8 g (females) and 21 to 124.9 (males). In both length and weight, females showed larger size than males. Age groups in both sexes were determined and ranged between 1 and 8 years. Monthly distribution of GSI for female and male P. stridens, showed that the GSI values have two peaks, the first one which was smaller occurred in December and the second one, the maximum, was in March. The minimum and the maximum of absolute fecundity were 28597 and 198672 per gram of body weight, respectively and the relative minimum and maximum fecundity was 288 and 1558 per gram of body weight, respectively. The mean of the sex ratio was 1: 3.3 (M/F). According to the GSI, ova diameter and histological observations, spawning period was determined from December to March.Stripped piggy (Pomadasys stridends) is widely distributed in coastal waters of Persian Gulf. However, the reproductive characteristics of this fish were under-researched. Specimens of Pomadasys stridens were collected from the local catches at Bushehr fishery harbor from May 2010 to April 2011, by regular monthly collections. A total of 540 specimens, including 155 males and 385 females were collected and transported to Bushehr fishery research center and then to Isfahan university of technology for analysis. The total length (in millimeter) as well as the total weight (in 0.1 grams) of the fish was carefully recorded. The total length of the mature fish ranged from 12.6 cm to 23 cm (females) and 11.7 cm to 22 cm (males) and their total weight ranged from 27.4 g to 144.8 g (females) and 21 to 124.9 (males). In both length and weight, females showed larger size than males. Age groups in both sexes were determined and ranged between 1 and 8 years. Monthly distribution of GSI for female and male P. stridens, showed that the GSI values have two peaks, the first one which was smaller occurred in December and the second one, the maximum, was in March. The minimum and the maximum of absolute fecundity were 28597 and 198672 per gram of body weight, respectively and the relative minimum and maximum fecundity was 288 and 1558 per gram of body weight, respectively. The mean of the sex ratio was 1: 3.3 (M/F). According to the GSI, ova diameter and histological observations, spawning period was determined from December to March.

Study of morphological characteristics and apparent differences are important in fish classification, comprehension of biological and feeding factors and growth. Therefore, the present study has been conducted to investigate morphometric and meristic characteristics of sharp nose mullet (Liza saliens) in Bandar Anzali coast from August 2012 to October 2012. According to data analysis, the average of total length, weight and age of the examined specimens (n=180) were 255.49±30.74 millimeter, 127.47±42.14 gram and 4.32±0.106 year, respectively. The average number of scales on lateral line, the number of branched rays in the second dorsal fin and anal fin were estimated 44.95±1.71, 7.04±0.45 and 8.92±0.35, respectively. Other measurements were as follows: the average head length 23.5±1.1%, eye diameter 6.25±0.5%, maximum length of body 21.47±1.86%, height and length of the first dorsal fin 12.36±0.95 and 6.04±0.53% respectively, height and length of the second dorsal fin 12.76±0.94 and 8.41±0.67% respectively, height and length of anal fin 13.26±0.96 and 9.51±0.85% respectively, pectoral fin length 20.02±1.19% and ventral fin 14.07±0.84%, pectoral-ventral fin distance 18.57±1.11% and ventral-anal 37.02±1.81% and pre-dorsal distance 48.96±1.61% of body fork length. Results showed that there were no statistic differences in meristic counts between male and female but there were observed differences in 40 morphometric factors between two sexes.