Iranian Scientific Fisheries Journal
Year:2014 | Volume:22 | Issue:4|Papers Count:14

Understanding the embryogenesis of Bunni is a useful tool for finding the time and suitable environmental conditions for spawning, growth requirements and use of techniques to increase the growth rate and survival. The stages of embryonic development for Bunnei (Barbus sharpeyi) was investigated in 22oC. The reared brood stocks were spawned in captivity condition. The oocytes were spherical, brown and very adhesive. The cleavage was fast and the first division was recorded within 15-20 minutes after fertilization. The blastulation and gastrulation were investigated in 7: 40 and 13: 10 hours after fertilization with the yolk sac diameter of 1.18±0.061mm (Mean±SD), respectively. The organogenesis was started 21 hours after the fertilization, when the blastopore was closed and notochord was formed. The embryonic stages were continued by appearance the brain, the somites and the melanophores on the yolk sac. The heart was beaten and shown the blood circulation 65 hours after the fertilization. The head, tail and pectoral fins were moved frequently. The embryo reached to pre hatching and final hatching 79: 10 and 84: 10 hours after fertilization, respectively, and the embryo existed from corion with the length of about 5.29±0.121mm (Mean±SD).

The widespread uses of antibiotics have been resulted in resistant strains of microorganisms and increasing of worldwide antibiotic resistance. Thus the investigations on new natural antibacterial agents as new drugs are important. According to the previous researches, some multicellular marine algae have significant antibacterial properties. In the present study, antibacterial effects of organic and aqueous extracts of Sargassum glaucescens (collected from Chabahar’s coast, Oman Sea, Iran) were tested on three strains of Gram-negative bacteria: E. coli, Proteus vulgaris, Vibrio cholerae and two strains of Gram-positive bacteria: Listeria monocytogenes and Staphylococcus aureus. Extractions were obtained by immersion method after 48 hours. Antibacterial effects were investigated by the disk diffusion method and serial dilutions in tube to determine the minimum inhibitory concentration. The ethanolic extract showed the largest impact on the L. monocytogenes with significant difference than that by the neomycin. Yet, the aqueous extract showed no effects. Ethanolic extract of algae had no effects on the Proteus vulgaris. The results of present study demonstrated that Ethanolic extract of S. glaucescens had reliable antibacterial effects against L. monocytogenes, Vibrio cholerae, E. coli and Staphylococcus aureus.

One of the most important bacterial fish diseases which have caused some outbreaks in rainbow trout farms in Iran is streptococcusis. The farmers have been suffering from huge economical losses due to the disease outbreak in different rainbow trout farms in Iran. The aim of present study was to determine the rate of streptococcusis incidence in different growth stage in the farmed rainbow trout in Haraz River in Mazandaran Province, Iran. Fish specimens along with water samples were collected from 10 haphazardly selected fish farms on a monthly basis throughout a year. After clinical observations, isolation and recognition of strep strains were undertaken using biochemical and PCR tests. The results showed that 4.6% of juvenile fish showed clinical sings of streptococcusis while only 0.7% had strep.contamination. These rates in adult specimens were 8.9 and 1 percent, respectively. The main isolated bacterial strain was Streptococcus uberis.

Spring viraemia of carp virus (SVCV), a negative sense single stranded RNA virus of the family Rhabdoviridae, is the causative agent of a highly contagious SVC disease that primarily affects the common carp (Cyprinus carpio), an economically important fresh water fish species with world-wide distribution. SVCV has also been reported to cause disease in other fishes such as Poeciliidae, Esocida, Centrarchidae, Siluridae and salmonidae. There are several diagnostic tests for the detection of SVC virus, however, the tests have not been validated. The reverse transcriptase – polymerase chain reaction (RT-PCR) techniques have been developed and validated representing a powerful tool for detection of RNA. One of the most important aspects isolating RNA is to prevent degradation of the RNA during the isolation procedure. In this study, we explored the efficiency of protocols for RNA isolation from the SVCV strain 56/70.For RNA isolation, we compared four protocols, two guanidine isotiocyanate phenol – chloroform based protocols (RNX – Plus Iran, Iq2000 kit Taiwan) and two column based protocols (Cinnapure RNA Iran, high pure viral RNA kit, Roche Germany) that were commercially available. The results showed that the column based protocols, Roche method and Cinapure performed better than other methods with the yields of 31.76 ng/ml, 16/21 ng/ml, respectively. Each protocol yielded good quality of total RNA bands (480 bp) being observed in agarose gel electrophoreses but was not observed in IQ2000 kit. Amount of total RNA isolated was lower for IQ2000 kit Protocol. Further, the RNA being extracted from SVC by column based protocol method were resulted in successful amplified using RT-PCR method.

The speciemns of red algae “Gracilaria corticata” were collected from the rocky intertidal shores in Bostaneh Port in the Persian Gulf and Lipar in Oman Sea in May, June and August 2013. Anatomical, morphological structures, thallus of vegetative and reproductive samples were studied. Carpogonial and tetrasporangium stages were determined based on histological and morphological methods. The female thallus, the Cystocarp with hemispherical structure through out thallus were observed. The Spermatangial conceptacle was located deeper as the oval shape in male thallus. The tetrasporophytic stage of diploid samples was determined by the presence of tetrasporangium oval shape.

The sub-lethal effects of water-born Cadmium (Cd) on histopathological changes of gill tissues were investigated on Sterlet, Acipenser ruthenus. In this research, 60 fish (41.69±0.95 g and 23.98±0.14 cm) were randomly distributed in 4 experimental groups, each with 3 replicates. The fish were exposed to different concentrations of Cd for 21 days under semistatic experimental condition as: 0, 16, 32 and 64 mg/L Cd. At the end of the experiment, the gill tissues were fixed in Bouin's solution for histopathological studies. Qualitative and quantitative changes of the gill tissues were analyzed. Several qualitative changes including hyperplasia, hypertrophy of epithelial cells and epithelial edema as well as necrosis, rings and fusion of gill filaments and secondary lamellae were observed in all treated fish including control group. Quantitative analysis based on organ index (Iorg) showed significant increase in histopathological changes in the gill tissues coincided by elevation of Cd concentration in the water. However, there was no significant differences in the organ index between control and 16Cd group. The results of this study demonstrate severe histopathological changes in the gill tissues after exposing to sub-lethal concentration of water-born Cd under experimental condition. The results of this study might be used as a guildline for evaluation of histopahological changes being induced by heavy metals in natural or cultivated environment for sturgeon fish.

The genus of saprolegnia is one of the most important pathogenic aquatic fungi in farmed and wild fish. In the present study, fungal infected egss were collected from rainbow trout (Oncorhyncus mykiss) and Caspian trout (Salmo trutta caspius). After purification, 16 isolates were obtained (8 isolates from rainbow trout and 8 isolates from Caspian salmon, respectively). The isolates were then coded as R2 – R9 (rainbow trout) and S2 – S9 (Caspian trout).The registered DNA for S. parasitica (ACTT # 200048) and S. diclina (ACTT # 4206) were used and coded as R1 and S1, respectively. Based on the RAPD profile obtained all samples were divided to 3 groups and members of each group had more than 90% similarity among themselves. According to matrix of similarity and reference strains, the isolates were classified as three groups. Therefore, all of isolates in group 1 and 3 were S.parasitica and S. diclina, respectively, and the members of group 2 were known as Saprolegnia sp. The results of thermal resistance assessment showed that the isolates of rainbow trout and Caspian salmon eggs had slow growth in the temperature between 18 – 20oC. Thus, R2 and S8 isolates had the lowest radial growth compared to other isolates. The isolates categorized in S. parasitica (group 1) created secoundry zoospores but not observed in two other groups. Thus, catenulated gamme was found in 78% and 55.55% isolates of rainbow trout and Caspian trout eggs, respectively. This study indicated that molecular methods were the best methods for identification of Saprolegnia spp. and it could be applied as a supplementary confirming method.

A total of 64 specimens of rainbow trout (Onchorhynchus mykiss) from 3 different regions in Iran were collected. About 2-3 g of caudal fin samples were removed from each specimen and preserved in absolute ethyl alcohol and transferred to the genetic laboratory. Genomic DNA was extracted using the phenol-chloroform method and then DNA content and quality was determined using spectrophotometry and agarose gel electrophoresis, respectively. Polymerase Chain Reaction (PCR) of genomic DNA fin samples was carried out using 8 pairs of microsatellite primers. All PCR products were electrophoresed on 6% polyacrylamide gel and stained with silver nitrate. Following the scoring of alleles, all parameters including effective number of alleles, observed and expected heterozygosity, shanon index, Hardy- Weinberg equilibrium test and FST were calculated using AMOVA analysis in the GenAlex and Popgene programs. The results showed that 8 pairs of microsatellite primers were polymorphic. In total, alleles were determined with the range size of 64-280 bp. The locus OtsG 249 had maximum number of allele (9) and loci OtsG 432 and OtsG 474 had minimum number of allele (2). The observed heterozygosity was between 0.869 and 0.916. Hardy- Weinberg departure was observed for most loci from all farms and were disequilibrium. The Fst results showed that maximum FST (0.079) were between farms in Tehran and Yasuj and minimum (0.041) were between farms in Hamadan and Yasuj. Based on the results of AMOVA analysis, significant differences were detected between all farms. The results suggest that the unique genetic variation of rainbow trout in hatchery farms of Iran represents a highly valuable genetic resource and provide useful information for creating a based population in the future breeding programs.

A 2×4 factorial design was conducted to study the effects of dietary protein and energy levels on growth performance of juvenile beluga (Huso huso) with average weight of 49.85±1.64 g. Experiments were conducted with two dietary protein levels (40 and 45%) and four dietary energy level (18.5, 19.8, 21.1 and 22.4 MJ/kg diet) by ratio P/E (18.03 to 24.14 mg/kj). Fish were fed the experimental diets for 110 days. In each of the protein levels (40 and 45%), the feed efficiency, body weight increase, Protein efficiency ratio, specific growth rate, final body weight and total feed intake of fish improved significantly as dietary energy levels increased (P£0.05). Growth of fish fed high- energy diets was significantly higher than those of fish fed low- energy diets at 40 and 45% dietary protein levels (P£0.05). Protein content of carcass increased when dietary protein increased, but there was no significant different (P³0.05) between 40 and 45% protein. Lipid content of fish fed diet high- energy level was significantly higher than those of fish fed low dietary energy (P£.05). So the maximum growth and weight (22.4±5.3 gr) was observed in treatment, that were fed diets containing 45% protein & 22.4 mega joule crude energy. Considering that no significant difference were affected for among the diet for the parameters studied, the diet containing 40% protein, 21% fat and 21.1 mega Joule crude energy per kilogram diet with a P/E ratio of 20 mg protein per kilo joule from a good quality source is a suitable diet in terms of physiology and economy can be considered a suitable diet to produce maximum growth in juvenile beluga in the weight class 49 to 200g.

In order to establish a complete list of the hermit crab species in the southern coast of Iran and also determine some of their biological characteristics in the intertidal zones of Hormuz Island, a seasonal sampling collection was conducted in 6 intertidal stations during the years 2010–2011. The 542 collected samples were found to be Clibanarius signatus, which identified in the island. Comparing the samples with the metatypical hermit crab samples in the Zoological Museum, University of Tehran, verified the species. The one ways ANOVA with LSD test showed a significant difference (p<0.05) in the abundance of the species in some stations, but seasonal changes did not significantly affect the abundance. Male-female sex ratio was 1.52 male: 1 female. Seasonal study of sexes (male, non-ovigerous female, ovigerous female) confirmed that species did not have a particular spawning season, nevertheless the spawning increased in summer. The shell selection behaviors showed that the hermit crab uses the shells of 36 gastropod species (24 genera) for protecting its abdominal section.

This study investigated the effect of parasite infection with Posthodiplostomum cuticola on fish growth rate in Zaringol Stream in Golestan Province. A total number of 447 fish specimens (173 Capoeta capoeta gracilis, 111 Alburnoides eichwaldii, 131 Paracobitis malapterura, 32 Neogobius fluviatilis) were captured by electrofishing during December 2009 to September 2010. Total number of parasite on fish body was counted by investigating internal organ and surface of skin and branch. Results showed that slope of regression curves and condition factor were significantly lower in infected C. c. gracilis. N. fluviatilis was the most abundant infected fish in Zarringol Stream,. It seems that it's feeding dependence on benthos makes this fish more susceptible to infection by parasite.

The new record of a puffer fish “Takifugu oblongus Bloch, 1786” (Tetraodontiformes, Tetraodontidae) is recorded for the first time the muddy shores of the inter-tidal zone of Bandar-e-Abbas city, in the northern Persian Gulf, Iran in March 2011. The morphological features of Takifugu oblongus are described. This species has previously been recorded from Indo-West Pacific, South Africa to Indonesia, Japan, China, and Korea (locality type). This finding considerably extends our knowledge of the distribution of Takifugu oblongus.