Effects of n3-HUFA enriched Daphnia magna on growth, survival, stress resistance, and fatty acid composition of larvae of Persian sturgeon (Acipenser persicus)

Effects of Daphnia magna enriched with cod liver oil (CLO) as a source of highly unsaturated fatty acid (HUFA) on growth, survival, stress resistance, and fatty acid composition of the Persian sturgeon larvae were evaluated. Daphnia enriched for three different time periods (3, 6, and 9 hours) and non-enriched Daphnia were fed to the Persian sturgeon larvae (average weight 61.6±0.4mg) during 14 days. The highest n3-HUFA content was found in Daphnia enriched for 9 hours (0.69mg g-1 DW) and the highest n3-HUFA content of the larvae was also found in those larvae fed with Daphnia enriched for 9 hours (2.39mg/g-1DW). A significant growth difference between larvae fed with enriched and non-enriched Daphnia was observed (p0.05). Furthermore, the highest pH stress resistance was found in those larvae fed with Daphnia enriched for 9 and 6 hours (p<0.05). A salinity stress test did not show significant differences among the treatments

Influence of supplemental phytase on fish meal replacement by soybean and its effects on growth and body composition of rainbow trout (Oncorhynchus mykiss)

Influence of phytase enzyme and replacement of fishmeal protein by soybean meal protein on growth and body composition of rainbow trout (Oncorhynchus mykiss) specimens each with a mean weight of 121.75~c5.95g were studied. Experimental diets by factorial method 3*3, containing three levels of replacement (0.0, 35 and 70%) and three levels of microbial phytase (0.0, 1000, 2000 units/kg diet) were formulated and prepared. Nine treatments and three replicates of random groups of 20 fish per each 2 cubic meter (2*2*0.5m) tank were used in the study. All diets contained 36-38% protein and about 4000 cal/g energy. During the 9 weeks period of the study, fish were fed to satiation level, three times daily. Statistical results indicated that the increase of replacement level to 35% had no significant effect on growth index (P greater than or equal to 0.05). Effect of replacement on body composition was not significant, except for crude energy which decreased in 70% level (P≥0.05). Effect of phytase enzyme on growth index was positive and 2000 units/kg diet of phytase showed the best result (P≥0.05), but phytase levels had no significant effect on body composition. Result also showed that there was a significant interaction between phytase enzyme and meal rep lacement (P≥0.05). We suggest using 2000 units/kg diets of phytase with at least 35% replacement of fish meal protein by soybean meal protein as a suitable formula for growing rainbow trout

Effect of the timing of initial feeding on growth and survival of Persian sturgeon (Acipenser persicus) larvae

Effect of the timing of first feeding (9, 10, 11, 12 and 13 days post hatch) with a live food (Artemia naupli) on Persian sturgeon was examined at 17.7±0.8 and 18.1±0.4°C. The results showed that the timing of first feeding affected on weight, length, length-weight ratio and specific growth rate, but one day delay in the timing of initial feeding doesn't affect on the survival and two days delay in the timing of initial feeding doesn't affect on the condition factor. Results of this research showed that some factors such as weight, length, length-weight ratio and specific growth rate, are more suitable than survival and condition factor for exhibiting of effects of delay in the starting time of initial feeding in Persian sturgeon fish larvae. Thus it is better that the initial feeding of Persian sturgeon at 17.7±0.8 and 18.1 ±0.4°C started on 12 and 9 days after hatching, respectively, as well as more delay in initiating exogenous feeding has negative effects on growth of larvae

Changes of digestive enzymes activity in common carp (Cyprinus carpio) during larval ontogeny

This study was aimed to gain knowledge on the ontogeny of digestive enzymes in common carp larvae at the governmental Warm Water Fish Aquaculture Center of Shahid Rajaee in Sari, Mazandaran, Iran. The ontogenetic development of pancreatic (trypsin, chymotrypsin, lipase and α-amylase) and intestinal (alkaline phosphatase and aminopeptidase-N) enzymes were assessed in common carp larvae from first feeding (3 days post hatching) to 33 days post hatching (dph). The larvae started to feed on rotifers at day 3 to day 7. Feeding on a commercial diet was started from day-8 onwards. Specific trypsin and chymotrypsin activities feed with rotifer were 0.011 U/mg protein and 0.003 U/mg protein at day 7, respectively; then the specific activities feed with dry food reached a maximum level at 33 dph (0.028 U/mg protein and 0.028 U/mg protein, respectively) (P<0.05) compared to live prey. The elevated alkaline proteases activity can be related to adaptation of larvae to digest protein content in the food. Specific lipase activity was 0.0006 U/mg protein at 7 dph; then the activity feed with dry food reached a maximum level at 15 dph (0.0011 U/mg protein) (P<0.05) compared to live prey. Specific α-amylase activity feed with rotifer was 85.86 U/mg protein on the 7 dph; consequently, its specific activity reached a maximum level at 15 dph (128.77 U/mg protein) (P<0.05). Specific alkaline phosphatase and aminopeptidase N activities feed with rotifer were 6 U/mg protein and 0.0106 U/mg protein at day 7, respectively; then the specific activities feed with dry food reached a maximum level at 33 dph (28.66 U/mg protein and 0.58 U/mg protein, respectively) (P<0.05) compared to live prey

Changes in growth and amino acid composition of Rutilus frisii kutum during larval development

The present study investigated changes in growth and amino acid composition Kutum Rutilus frisii kutum during larval development. For this purpose, the periodic sampling from larvae obtained from breeders propagation was carried out at the fish aquaculture center of Shahid Rajaee in Sari. The samples were obtained at 1, 3, 7, 10, 15, 20, 25, 30, 35, 40 and 50 days after hatching (DAH). The result of larvae growth showed that mean initial and final length of Kutum (1 DAH, 50 DAH) were 8.47±0.02mm and 35.34±0.41mm, respectively. Initial and final weights were 4.02±0.01mg and 483.33±1.11mg, respectively. The composition of total amino acids of Kutum larvae changed significantly during ontogeny. High correlations were found between rotifers and dry food but correlations dry food was higher than that rotifer. No major imbalance was found in essential amino acids profile of the diet of fish larvae. Nevertheless, low correlation of rotifer to dry food in rotifer AA nutritional balances was less than dry food. During this study, methionine, lysine, arginine, threonine and histidine appeared to be limiting amino acids. These fatty acids showed the significant difference between the amino acid profile in larva and the diet

Acute LC50 and bioconcentration of mercury chloride in Rutilus frisii kutum

To determine the acute toxicity and bioaccumulation of mercuric chloride in Rutilus fidisii kutum, specimens of the fish were exposed to various concentrations of the chemical in water. We carried out ten treatments with three replicates and one control for each of the chemicals using the static 0.E.C.D. method in 55 liter tanks each containing 14 fingerlings. During the experiments, the average pH was recorded as 7.8, total hardness was measured to be 255 mel, average water temperature was 27±1 degrees centigrade and dissolved oxygen was 7.2 mg/l. Mean LC50 values of Hgcli for juvenile R. fish kutum with mean weight 1± 0.2 grams were 0.102 and 0.086 mg HO at 24h and 96h, respectively. The bioaccumulation values during 24h in muscle tissue, kidney and gill were 1.55, 16.1 and 22.7 mg He respectively. The values during 96h exposure were 2.8, 16.8 and 26.65 mg He in tissue, kidney and gill respectively. The bioconcentration values for muscle tissue, kidney and gill during the first 24h were 14.75, 153.39 and 216.11 after 96h were 33.8, 198.1 and 313.5 times that of the environment. These results show the bioaccumulation to be the highest in gill followed by kidney and muscle tissue. The study suggested direct relationship between mercury concentration in and its bioaccumulation in the fish organs tissue

Study on the changes of some physiological factors during osmoregulation of juvenile Persian sturgeons (Acipenser persicus)

Experimental trials of acclimatization of juvenile Persian sturgeon, Acipenser persicus to different salinites of 0,5,10, 15ppt were studied. The juvenile Persian sturgeons in three weight classes (1.5, 3, 5g) have been transfered from freshwater to different concentrations of saline water. Na+, k+, Cl- concentrations of blood serum and the changes in the number and size of chloride cells were measured. Na+ concentration showed an imperceptible trend and K+ concentration had a decreasing one size of changed chloride cells in different salinities were 8.6-13±0.3 μm and their numbers were (25-65±3) in 5 pairs of fillaments. The results revealed that salinity tolerance was increased with the fish size. According to this study, there is a direct relation between the number and size of chloide cells and salinities and time exposure

Effects of egg size on length, weight, growth and survival of prelarval and early feeding stage of Persian sturgeon (Acipenser persicus)

A study was conducted on the effects of egg size on length, weight, growth and survival of prelarval and early feeding stages of 19 female breeders of Persian sturgeon. The results showed that egg size can affect the total length and weight of prelarvae and there were positive and significant correlation between egg size and total length of prelarvae at the hatching stage and at 2,4,6,8 and 10 days post hatching (P<0.05). There were also positive and significant correlation between egg size and volume of yolk sac at hatching (P<0.05). However, during the first feeding stage the correlation between egg size and survival was very weak

The comparison of LC50 of clove essence and MS222 in Acipenser persicus, Oncorhynchus mykiss and Cyprinus carpio

The LC50 of two anaesthetic agents, clove essence and MS222, on the cultivated fish species, Acipenser persicus, Oncorhynchus mykiss, Cyprinus curpio were estimated. 640 samples of above mentioned species were used exposing anaesthetic agents for 2 minutes.LC50 of clove essence and MS222 for sturgeon estimated 297 and 291 ppm, for common carp was 271 and 272 ppm; and for rainbow trout Was 199 and 207 pmm, respectively. Significant difference was found only between LC50 of MS222 in rainbow trout with LC50 of both agents in two other species. Also, the results showed that there is no significant difference on poisoning of two applied drugs in all above mentioned species; with comparing different species, rainbow trout had lower tolerance to both anesthetics