Journal of Aquaculture Development
Year:2015 | Volume:9 | Issue:2|Papers Count:8

The aims of this study were to examine the impact of density and diet on rates of growth, survival and body composition of big head (Hypophthalmichthys nobilis) larvae at Dr.Keivan Fisheries science Research center and Marine Techniques (Chamkhaleh port) for 21 days. To perform this experiment, three different densities (25, 50, 75 larvae per liter) with three different diets (Artemia, Daphnia and Artemia-Daphnia mix) in 9 treatments with 3 reiterations in each were considered. Results show that in feeding big head (Hypophthalmichthys nobilis) with 3 types of diets and 3 different densities, the type of had a significant effect on each factor of growth (FBG, DGR, BWI, SGR) (p<0.05). Though all treatments showed significant differences, the best rates of growth were observed inArtemia diet as well as Artemia-daphnia mix. There was also a significant differences in survival rate between treatments (p<0.05). Percentage of survival of larvae feeding on mixed diet (Artemia and Daphnia) and Artemia in low density was higher than fish fed in high and average densities. There were maximum mean of protean of body in the low and medial density feeding with Artemia than other treatments. Density and feeding no effective on fat and humidity of body composition. Results showed that Artemia and Artemia-Daphnia mix were suitable feeds for the active feeding stage of big head (Hypophthalmichthys nobilis) larvae.

Present study identified and investigated the abundance types of live food in the earthen ponds of Persian sturgeon fry and stomach contents of 240 pieces of them. How to select of food by fry, according to the food selection index for each food organism in six time of sampling were studied in earthen ponds. For this purpose sampled from zooplankton and benthos of Ponds and stomach contents of Persian sturgeon fry. The food selection index range from -1 to 1. Between the live foods that observed in ponds, Rotifer, and Daphnia were dominated with an abundance 172.6, 123.8 (number/m3) in sixth time sampling. The Chironomidae larvae had a highest level of abundance 40.25 (number/m2) in third time sampling. positive selection index showed the highest rate of Daphnia (0.83) in third time and for Chironomidae (0.59) it was in sixth time. To investigate the relationship between the abundance of food organisms and food selection index correlation coefficient (R) in the Pearson correlation coefficient test was used. Abundance of Daphnia ponds and food selection at 0.01 percent level showed a significant positive correlation (R= -0.939), while between the abundance of Daphnia stomach contents and index food selection, didnʼt observe significant correlation (R= -0.094). There wasnʼt a positive correlation significant between the abundance of Chironomidae larvae in ponds and food selection index (R= -0.079), while observed significant positive correlation between the abundance of Chironomidae in stomach contents and food selection index at 0.05 percent level (R= 0.884). The results persent study showed that, Daphnia and Chironomidae larvae were dominant foods in stomach contents and were selected by fry. Rotifer and Naply of Copepoda didnʼt observe in Stomach contents. The composition of Persian sturgeon fry diet in ponds was characterised by high proportion of Chironomidae larvae, which corresponds to the benthivorous feeding habits in this species and was supported by the results of the food selection index.

This study was performed to investigate the effect of stocking density on growth performance, feeding and water quality parameters to determine an optimal stocking density for rearing of hybrid of Asp (Aspius aspius ♀) × Kutum (Rutilus frisii ♂). Fish with mean initial weight of 60.41±0.04 g (±SE) were reared at five stocking densities of 2, 4, 6, 8 and 10 kg m-3 (20, 40, 60, 80 and 100 fish tank-1) for 8 weeks. At the end of rearing period, the highest mean body weight was obtained at 10 kg m-3 and the lowest at 2 kg m-3 (P<0.05). Growth parameters including mean weight, weight gain, average daily growth, specific growth rate and condition factor were significantly increased with increasing stocking density (P<0.05). Increased stocking density significantly increased feed intake (P<0.05), while feed efficiency, protein efficiency ratio and lipid efficiency ratio indicated no significant differences among different treatments (P>0.05). Water quality parameters including dissolved oxygen, pH, total ammonia, total nitrate and total nitrite were similar and did not show any significant differences among different densities (P>0.05). According to the obtained results, it seems that rearing of this hybrid at the density of 10 kg m-3 or more is possible without any negative impacts on growth performance and feeding.

An 8-week feeding trial was carried out to evaluate the effects of dietary L-Carnitine (0, 500, 700 and 1000 mg/kg) on growth performance, body composition and hematological indices of juvenile Acipenser nudiventris. A total of 120 Acipenser nudiventris averaging 49.36±1.27 g (mean ± SD) were randomly distributed into 12 fiberglass tanks of 500 L capacity and fed 3% pf body weight per day with diets contain 45% protein and 20 MJ/ Kg energy 3% of body weight respectively. At the end of the feeding trial, there were no significant differences (P>0.05) in final weight, body weight increase (%BWI), specific growth rate (SGR) and feed conversion ratio (FCR). But carcass protein content improved with increasing dietary L-Carnitine (levels 750 and 1000 mg L-Carnitine) (P<0.05). Total protein content and LDL of fish fed 500 and 750 mg L-Carnitine were higher than those of fish fed other experimental diets. Significant increases in hemoglobin and hematocrit were recorded in fish fed 750 and 1000 mg L-Carnitine (P<0.05). The results obtained from this study indicated that the dietary L-Carnitine had positive effect on fish biochemical index and body composition and seems a dietary 750-1000 mg/kg for juvenile Acipenser nudiventris Is benefit.

This study was conducted to evaluate the amount of moisture, protein, lipid and ash of wild and farmed Azolla (Azolla filiculoides) for nutritional application of livestock and human. Fatty acid composition of Azolla, a key component for making decision about the nutritional value, of both Wild and farmed types was also compared. The Azolla samples were collected from Pirbazar region, Anzali Wetland and cultured in aquarium containing appropriate medium to consider the process of growth and propagation. The fatty acid composition of wild and farmed samples was determined according to the Folch method for GC Analysis after the lipid esterification. No significant difference (p>0.05) was observed between wild and farmed Azolla in the amount of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs). However, palmitic acid, margaric acid, oleic acid, cis-linoleic acid, and a-linolenic acid of wild Azolla was significantly higher than farmed type (p<0.05). In contrast, lignoceric acid amount of farmed Azolla was significantly (p<0.05) higher than wild Azolla. Given the appropriate amount of lipid, both types of wild and farmed Azolla could be used as feed for livestock, poultry and even human, although wild Azolla had more lipid content compared to the farmed type. Furthermore, speed of propagation followed by the short doubling time of Azolla in vitro provides the ability for adequate amounts of oil extraction from this fern.

In this study, the Hepar s.C30 and erythromycin effects on cultured rainbow trout (Oncorhynchus mykiss) with experimental streptococcosis were compared for 2 week. 2treatment and 2controls and each of them with 2 reviews with 15 centigrade degree in 300 liter tanks that each of them contained of 40 juveniles rainbow trout fish with 25±5 g arranged weight was estimated. Pure culture of S. iniae in sheep blood agar and 400 juveniles of rainbow trout fish were adapted in 3 days and in forth day, the juveniles were injected with 106 of S. iniae in 1ml of physiologic serum in the peritoneum of all juveniles spontaneously. After 24 hour, some of symptoms occurred, and the remedies were prescribed: Treatment 1: 0.1g erythromycin (20percent) for 1kg of the juvenile’s weight, with fish meal. Treatment 2: one glob of Hepar s. C30, in the water, (every morning at 8 am, the circulation of water was stop for half hour for bath, then 1 glob of the remedy were put in the water, at 8.30 the circulation of water started again). Treatment 3: (control) without any injection and any therapy. Treatment 4: (positive control) with injection but without any therapy. Daily estimation of chemical factors such as the water temperature, oxygen, pH and salinity in the controlled situation for rainbow trout. Daily estimation of survival & mortality of the juveniles. Pathological symptoms were such as: necrosis and hyperplasia of gills; melanosis dots in liver, kidney; hart, kidney were bloody and clinical symptoms such as: exophthalmia; hemorrhages under the skin, eyes, gills and anus. Treatment 1 had significance with treatment 2, control and positive control (p<0.05).

The increasing level of pollutants such as pesticides has destructive impact on ecosystems and aquatic organisms. Juveniles of Acipenser persicus were exposed to sub lethal concentrations of endosulfan (10, 20 and 40 mg/l) during 14 days. For gene expression study sampling were done from the both liver and gill on day 1, 2, 7 and 14. Result showed that in gill and liver, the relative HSP70-mRNA expression level significantly increased (P<0.05) in all studied days compare to control. Relative HSP70- mRNA showed a clear time- dependent response in both tissues after exposure to endosulfan. A significant increase (P<0.05) were observed on the second day, then decreased on day 7 and increased on day 14. The same trends were observed in all studied concentrations (10, 20 and 40 mg/l), in both examined tissues. In this study although up expression of HSP70- mRNA was common to both the gill and the liver, it significantly (P<0.05) expressed in the liver more than the gill. The amounts of mRNA expression were increased in the highest concentration in all studied days in this investigation. Histopatological study of gills showed that the intensity of lesions were increased gradually in all concentrations during the time exposure up to day 7 and then negligible changes in the index of lesions were observed on day 14 compare to day 7. The intensity of changes follows a concentration- dependent manner and 40 mg/l-treated fish samples showed the sign of lesions more severely than 20>10 mg/l that verify the genetic results.

One of the problem sintensiveaquaculture is challenge of fish with stress such as manipulation and transition that lead to stress responses, followed by impairment of growth and survival. In the present study, the effect of handling stress on some hematological and biochemical indices was investigated in Mesopotamichthys sharpeyfingerlings. 30 M. sharpey (9.8±0.1 cm and 10±1 g) were exposed to air for 60 seconds. Fish immediately anesthetized with 2- phenoxy ethanol 0.2% and blood samples were obtained. Results showed a significant increase in glucose and lymphocytes number but glucose, total protein and monocytes showed a significant decrease (P<0.05). The increasein the electrolyte values and numberof neutrophils and adecrease inlactate was recorded, However these changes did not significantlyalteredin compare to pre-manipulation values. Findings showed that air exposure for 60 second caused to hematologic responses. Our findings showed that air exposure for 60 seconds activate stress axis and onset primary and secondary responses in M. sharpey.