نشریه علوم آبزی پروری پیشرفته
سال دوم شماره 2 (تابستان 1397)

This experiment was conducted to evaluate the effect of different levels of commercial prebiotic of liquid Celmanax on growth performances, feed indices and challenged with environmental stress of Cyprinus carpio fry for 60 days. This experiment conducted in a completely random design with five treatments which contain triplicates. Four levels of prebiotic (0.3, 0.5, 0.7 and 1 cc.kg-1 of ration) were added to the basic diet with a control that was devoid of prebiotic. At the end of the experiment the results showed that, the use of Celmanax liquid in the diet of carps fry, especially at high levels, improved FW, FL, WG, ADG, PBWI, SGR, CF, SR, HIS, FCR, FCE, PER and LER significantly (p<0.05). But, there is no any significant difference between treatment's feed intake (p> 0.05). However, by measuring the resistance of carps fry to environmental stress conditions there was no any significant difference between experimental treatments in compared with the control group against acid pH (pH=2) and basic pH (pH=12) tests (p<0.05). But, increased fry resistance against high ammonia (5 mg/l) and high thermal (40 C˚) tests in treatment affected by prebiotic, and the highest resistance was recorded in treatment containing 1 cc.kg-1 liquied Celmanax (p<0.05). In conclusion, based on the results we could claim that addition of high level of liquid Celmanax (0.7 and 1 cc/kg) in supplemented diet of Cyprinus carpio fry’s improved growth performance, feed efficiency and resistance time to the challenge tests.

Due to the rapid increase in human population, the need for food sources is also rising sharply. Aquatic organisms are one of the most important food sources. Due to no change in catch rates and even reducing in fish stocks, the way to achieve this amount of food is aquaculture. Other factor affecting the growth of the aquaculture industry, is its role in providing healthy and high-quality food products. One of the most important characteristics of edible aquatic animals, in evaluating its quality, is suitable color. Because of the high cost of creating and maintaining quality of colors in aquatic animals and also importance of color in the quality and economic value of aquaculture products, the aim of this study was to identify factors affecting the efficiency of carotenoid pigments on aquatic animals. The results showed that many factors affect the efficiency of carotenoids in aquatic animals, such as characteristics of aquatic species (species, sex, age and weight of species), type and source of the pigment, dosage and purity of the pigment, matrix in which the carotenoid is incomorated, amount and composition of diet, time and frequency of feeding, environmental factors (temperature, light, salinity), genetic factors, etc. This means we can not have a correct impression of carotenoids efficiency, without evaluating the interaction of all factors mentioned.

Improved growth, nutritional efficiency and resistance aganist diseases are among the most important goals of the aquaculture industry. Sustainable aquaculture development requires the use of novel techniques mainly including the use of probiotics to optimize the physiochemical factrors of rearing environment and improving the animal performance. In this regard, the isolation of biologically active bacteria from the intestines of farmed fish and the use of commercial products of such beneficial bacteria as an important strategy for biocontrol and bio-enhancement of aquatic animal performance would play a very important role in achieving aforementioned objectives of the industry. However, using ingredients which are not of nutritional importance to aquatic animal per se (prebiotics), while are beneficial to probiotic bacteria (synbiotics) can be effective in improving immune system of aquatics.

In this study some biological aspect of Chab (Squalius turcicus) was investigated in the Taham reservoir lake in north of Zanjan. The study of length and weight structure of dominated fish species, the Chab displayed a high length and weight. A number of 251 Chab were studied that the maximum size and weight were measured about 40 cm and 870 g, respectively with average weight 223 ± 204 gr. About 40% of fishes were weighted more than 250 gr which they were ranged as commercial size. The growth model was isometric and the condition factor was varied between 0.74 to 1.85. According to reproduction indices, more than 80% of ovaries were in 3 and 4 of the maturity stages in autumn that can reproduce in next spring. These characteristic and high distribution of species in Iran and special in the Caspian Sea area can be a reason to introduce this species as a candidate for aquaculture purposes. Thus, there is need the additional studies on conservation, breeding and rearing of species for fisheries approches and the sustainable exploitation.

When aquatic organisms expose to the stress condition, many processes of physiological, biochemical and molecular are changed undesirable, which one of them is heat shock proteins (HSP) expression. HSPs are unique group of proteins which act as a defensive barrier while expose under stress conditions results in degradation or deformation of proteins preventing. HSPs are significantly important in aquatic organisms. Since the farmed aquatic organisms are enabled to adapt the environmental stressful conditions, including temperature and pathogenic stressors. Although increasing level of this group of proteins is mainly observed by increasing temperature, however their expression has also been reported in response to low temperature. Increasing the level of these proteins can increase growth, survival and resistance to environmental stressors. In aquaculture, by artificial stimulation of production in this group of proteins or supplying feed containing HSP, the immune system can be improved against pathogens, and even as an alternative to antibiotics and vaccines in the aquaculture industry. This study reports the role and function of HSPs in aquatic organisms in aquaculture conditions.

During  planktonic  exploration  in the  study of the construction of coldwater fish culture in Zayandehrood  riversides  during 2007-2008, it showed that  the  plankton of this river has a low frequency and diversity. Planktonic  sampling  was  carried out  at 7 stations  and  along  the river. The plankton sampling  method  was designed  to  measure, Phytoplankton were collected for a liter of water directly , for  Zooplankton  samples  30 liter  of  water  were  filtered  by 55 micron zooplankton net(Apstein net). Samples were preserved with formaldehyde at % 4 concentration for analyses in the laboratory. In phytoplankton  study  of  this  river, 4 phylum  and  25  species  have been identified. The  most commonly  observed  species  belong  to  Bacillariophyta, The most important  of  genus  this phylum were  Navicula, Cymbella and  Nitzschia. Bacillariophyta  accounts for 94.7% of the annual Phytoplankton  frequency  in  this  river. 6 Phyla  and  29  genera were identified in  zooplankton study, the  most  frequent  of  which  was  Protozoa  and  the  most  diversity  was  related to phylum Rotifera. The  results  of  zooplankton  study  show Protozoan domination with %74.2 of  zooplankton  population (Ciliophora %51.8 and  Rhizopoda %12.7) which  has  the  most  frequency. The  most  important genus of  Rhizopoda was  Difflugia, Arcella, and  Centropyxis.  establishment  fish culture  along the rivers was commonplace in world, so the development and revision of river fortunes is essential for proper exploitation  of  these  water  resources in  aquaculture, while maintaining the health of the river ecosystem necessary .

Tilapia is an important candidate for aquaculture in saline water and one of the valuable commercial aquatics. Its development has been remarkable because of the unique biological characteristics, in recent years. In 2016, around 5.6 million tons of Tilapia were produced in 140 countries. China is the largest producer and the United States is the largest importer and consumer of Tilapia. Tilapia is introduced to iran as frozen fillets and has a good market penetration. Tilapia fish meat has a significant variation in unsaturated fatty acids, an optimal ratio of omega-3 fatty acids, and omega-6, and a suitable source of protein, calories, calcium, iron, and phosphorus. It is also a very suitable source for providing a variety of carotenoids. The US Food and Drug Administration and the US Environmental Protection Agency have recommended Tilapia as a suitable aquaculture for pregnant and lactating women and children. Development of tilapia production can play an important role in increasing the per capita consumption of fish as a healthy and high quality food.