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The fish diversity and distribution investigated in the Mahabad-Chai river of the Lake Urmia basin, over the years 1998-1999. Gillnet, beach seine, cast net and electro-shocker used to catch fishes seasonally in 16 stations within 5 regions of the river. We identified 18 species of fish belonging to four families of the bony fishes. The family Cyprinidae with 15 species was the most abundant comprising 98.2 % of the catch, present in all the stations. Families Balitoridae, Siluridae and Poeciliidae were represented only by one species and were the least aboundant, with the Balitoridae being present in all the stations. Of the identified fish species, Capoeta capoeta was the most aboundant, Chalcalburnus atropatenae was the second most abundant and Acanthalburnus urmianus was the third most abundant comprising 41.61%, 34.16% and 7.91% of the catch respectively. The least aboundant species were Abramis brama and Gambusia holbrooki with other 13 species coming in between in all regions while other species were present only in some of the regions. Of the identified fish species 11 were native and seven were alien species introduced by Caspian Sea Bony Fishes Research Center. Presence of Pseudorasbora parva and Rhodeus sericeus amarus reported for the first time in the region. Also, among the identified fish, Leuciscus ulanus, Ch. atropatenae and A. urmianus are endemic to Iran, living in the Lake Urmia basin. Having a small stock and narrow distribution in the wild, the Leuciscus ulanus is of especial importance to the fishery managers.

This study was conducted to determine growth parameters, catch and fishing effort trends, stock assessment of Caspian Sea mullets in the Iranian coastal waters of Caspian Sea in the fishing season of 2013-2014. For gathering of data on biometry and catch statistics, 5 mobile working group in the regions of Anzali, Kiashahr, Noshahr, Babolsar and Torkmen were involved from the start to the end of fishing season.Gathered data Were entered to the computer. For data analysis, common methods were undertaken for estimation of growth parameters, mortality rates, biomass and Maximum Sustainable yield (MSY) as well. According to the result, the number of beach seines cooperatives was 124 and fishing efforts were 44688 beach seining haul. The catch per unit of effort CPUE) was calculated 53 kg/haul during this fishing season. The total catches of Caspian Sea mullets (including illegal fishing estimated as 2373 mt. Growth parameters of golden gray mullet (Liza aurata) were estimated as K=0.16/yr, L_∞=57.4 cm, t_0=-0.45/yr. Based on catch-at-age data, in the fishing season of 2013-2014, the total biomass, from the biomass-based cohort analysis were estimated 12473.3. mt. Based on these results, the fishing mortality rate in fishing season of 2013-2014 were 0.575/yr. In this survey, the Maximum sustainable yield were estimated as 2558.6 mt respectively. Generally from three Northern Province’s cooperatives 3406 samples collected. Results of biometry of golden gray mullet (Liza auratus) showed that the mean length and weight and age of this species were 32.3±6.1 cm and 383.5±74.823.4 g and 1.2±5.6 y respectively and leaping gray mullet (Liza saliens) showed that the mean length and weight and age of this species were 24.8±3.3 cm and 119±25.5 g and 2.5±0.6 y respectively. The biometric results showed that, 97.5% of the samples belonged to golden gray mullet and population of leaping gray mullet was sever declined. Also, the fishing of the mullet was increased over the last year by 10.3 % from 2151 tons to 2373 tons per year during 1391-92 and 1392-93, respectively .

The overfishing and changing environmental following the introduction of the comb jelly Mnemiopsis leidyi in the Caspian Sea, the population structure has a strong influence on kilka fishes in the Caspian Sea and therefore to in this investigation which had been done in commercial catch regions (where discharged theirs catch) in three ports Babolsar, Amirabad (in mazandaran) and Anzali (in Guilan), stimated catch and catch per unit effort, the age structur of catch, length- weight relationship, von Bertalanffy growth parameters, condition factor, sex ratios, maturity stags, spawning and feeding. The result shown that catch of kilka in Iranian coastal in 2012 decreased from 24080 ton to 22696 ton in 2013. But CPUE increased was 2.7 ton (Vessel ×Night) and there was no significant changes. Common kilka was the predominant all months of the year, 98.1 and 98.9 percent in 2012 and 2013 respectively. The mean length was 104.4±10.5 and 101.6±11.2 at the same time and range length 92/ 5 – 117/5 mm were the dominant population(about 75%). Relative abundance of fish less than 77.5 mm and more than 127.5 mm is very low. Age abundance during this period have not been substantially changed and always fishes with 3 and 4 year olds had the highest frequency73.6 and 73.5 percent respectively. The parameters of the Von Bertalanffy growth curve were ] exp1[8.141 ) 048.1(297.0  tLt for common kilka. The instantaneous coefficient of natural mortality (M) was 0.506 yr-1. The instantaneous coefficient of fihing mortality and total mortality were 0.694 yr-1 and 1.2 yr-1 , respectively. The exploitation rate of common kilka varied during 2012-2013 between 0.41-0.50. The mean condition factor 1.41±0.14 (n=5801) and 1.38±0.16 (n=6754) at the same time respectively . According to statistical analysis Anova oneway were a significant difference between condition factor at the same time . Main prey common kilka was Acartia tonsa accounting for over 80%. It seems Common kilka due to a decrease in the frequency of other zooplankton species depend more than ever on Acartia tonsa and this species is probably a concentration of prey for Common kilka. Iranian Fisheries Science Research Institute Published

According to the importance of micro-algae in aquatic feed such as fish in this study have been investigated Preparation of useful algae powder or concentrate for breeding silver carp , their impact on the growth of silver carp , rate per unit area and estimate n economic Development. Different algal species were isolated from hydrothermal fish farms, then were purified and mass culture . The next step microalgae were dried and powdered by spray dryer and were examined the fish feeding on them. During this study, 6 species of chlorophyt( Scenedesmus obliquus, Scenedesmus acuminatus, Chlorella vulgaris, Pediastrum boryanum, Pandorina morum, Ankistrodesmus falcatus) ,3 species of cyanophyta ( Anabaena flosaquae, Oscillatoria agardhi and Spirulina platensis) and 1 species of Bacillariophta ( Cyclotella meneghiniana were isolated from.Green algae and Blue -green algae were cultured in Zaindr medium, diatoms were cultured in Zaindr medium but with water of Anzali logoon and also in F2 medium with artificial sea water and spirulina was cultured in Zarouk medium. Microalgae were cultures then concentrated.Then the impact was examined on fish silver carp 2 to 3 grams. The results showed that Cyclotella has a greater role in the growth of silver carp and Anabaena floes aquae and Spirulina platensis tend to growth less than cyclotella. Scenedesmus obliquus and Scenedesmus acuminatus were respectively next algae that showed the greatest impact on fish growth. Scenedesmus obliquus feed rate was greater than any other algae for Daphnia.

The Isolation , Purify , semi mass culture and mass culture of algae was started in bony fishes research center of Guillan from 2001-2004.during this survey 39 species of algae stock remained that all of them were pirified. Some of economic valuation of algae were studied ,forexample: food for aquaculture , protein, lipid and toxin extraction and antibacterial property. The result showed that Rodomonas sp. Initiate the most of growth and survival for Daphnia magna because this species have a lot of unsaturation fatty acid (w3) , also the species of cyclotellasp. was fed better than other algae by silver carp in this survey . amount of toxin was a little in most of algae. The species of Anabaena spp1. , Anabaena flos-aquae have Antibacterial property but Anabaena bergii, Nostoc caraneum and Oscillatoria affricanum have antifungal property.the both Antibacterial and antifungal property observed in Anabaena variabilis , Anabaena spp2.and Anabaena spp3.amount of protein in green and blue-green algae wasrespectively 51±8 and 60±10 percent of dry weight . Total lipid amount was 12±0.4 , 8±0.3 and 2±0.8 percent of dry weight respectively in chlorella vulgaris, Scenedesmus obliquus , Anabaena flos- aquae. Iranian Fisheries Science Research Institute Published

The likely effects of varying Calcium concentrations on the growth and biomass production of Chlorella vulgaris algae have been studied during 2003-2004 in the Bony Fish Research Centre in Guilan Province, Iran. We cultured pure Chlorella vulgaris stocks in Zinder media applying seven Calcium concentrations as treatments, 3 replicates for each treatment and one control. The laboratory experiments lasted 96 hours during which the temperature and light intensity were kept at 25±2 degrees centigrade and 3500±350 lux respectively. Spectrophotometer assessment of the samples at a wavelength of 750 nm and visual counting at the start and end of the experiments were carried out to assess the growth and biomass of the green algae. Statistical analysis of the results in SPSS software showed the effective Calcium concentration to be between 0.1 to 15 mg/l while the highest growth of the algae was reached at 2.8 mg/l where as in control group (Z-8±N) the amounts was 9.2 mg/l. Density of the algae was 17575675 cells per milliliter of the culture medium and the absorption rate was 0.542 and algae biomass was 17676 cells per milliliter. Calcium concentrations above these rates can have a negative effect on the growth and biomass production of the algae.