---

  Apparent digestibility coefficients (ADC) were calculated by using chromic oxide in the diet as an indigestible marker to evaluate the Iranian Cottonseed meal (CSMP) . Then, the nutritional value of cottonseed meal ( ‍ CSM) as soybean meal (SBM) substitute in quality low cost rainbow trout (Oncorhynchus mykiss) ration was investigated. In this study, six formulated feeds consisting different levels of CSMP (0, 20, 40, 60, 80, 100%) substitution of SBM were fed to a total of 540 rainbow trout with initial mean body weight of 50 ± 5 g. Fish were randomly stocked into eighteen 100L fiberglass tanks with 30 fish per tank and 3 tanks per diet and fed to apparent satiation 3 times a day and 7 days per week for 60 days. The ADC of CSMP and SBM were measured as of dry matter, 62.7 and 69.2% crude protein, 82.4 and 87.3% fat, 66.6 and 78.5%, respectively. After an 8 week feeding trial, the average weight gain of fish fed with diets 1 to 6 was: 100.6, 102, 102.9, 103.3, 103.9, and 103.4g, respectively. Average feed conversion ratio (FCR) of fish fed diets 1 to 6 was measured as of 1.28, 1.31, 1.31, 1.27, 1.29, and 1.25, respectively. For all six treatments, the survival percentage was more than 99%. ADC value for most nutrients of CSMP was different from those of SBM. Weight gain, specific growth ratio (SGR), daily weight gain (DWG) and survival rate were not significantly different (P>0.05) for fish fed with CSMP diets compared to the control diet but the differences of FCR were significant among different diets (P<0.05). In the feasibility study, complete replacement of SBM by CSMP revealed to be economic and based on the gossypol analysis, total gossypol levels was not observed for toxicity on liver of fish fed by CSMP, indicating the possibility of total replacement of SBM by CSMP in rainbow trout fed formulations.

---

Three different varieties of cottonseed meal (CSM) were evaluated to measure the apparent digestibility coefficient (ADC) of the nutrients using chromic oxide (Cr2O3) as an indigestible marker. Five experimental diets were prepared and mixed with 1% of Cr2O3, 2% of mineral and vitamin each of which were premixed. Diet 1 was used as the control diet. Diets 2, 3, 4 and 5 were formulated using 70% of the control diet together with 30% of each ofthe cottonseed meal Pak (CSMP), cottonseed meal Sahel (CSMS), cottonseed meal Akra (CSMA), and soya bean meal (SBM), respectively, in three replications.The ADC of the three CSM varieties was measured to be 53.8-62.7%, 60.2-66.6% and 75.6-82.4% for dry matter, fat and crude protein, respectively. Survival rate for all fishes used in this study was more than 98%. Fishes fed with the CSM diets were not significantly different compared with those fed with the SBM diet in terms of survival rate (p>0.05). Apparent protein digestibility of CSMP and CSMS showed no significant difference with SBM (p>0.05). Therefore, it could be concluded that two kinds of CSM could be used as a replacement for SBM in rainbow trout as a protein source.

---

The effects of n-3 highly unsaturated fatty acids (n-3 HUFA) were studied on Beluga (Huso huso) fish larvae by feeding fish larvae with live food  enriched with 4 different oils (ICES 30/4, tuna eye oil, flaxseed oil and linseed oil) containing different levels of n-3 HUFA including 27.19, 20.33, 12.71 and 0.39 mg g^-1 dry weight of oil, respectively. Fish larvae weighing 30.00±2.00 mg were randomly divided into 12 groups of 150 fish each and triplicates fed the 4 experimental diets for 3 weeks. There were no differences in survival rates, but significant differences were found in growth rates and fatty acid composition of the fish larvae after 30 days. Fish fed low levels of dietary n-3 HUFA (0.39 mg g^-1 DW) showed poor n-3 HUFA contents but these fatty acids improved with the elevation of the n-3 HUFA levels in the diet up to 20 mg g^-1 DW. Fish fed the flaxseed oil showed the highest level of crude lipid 15.00±3.01). Results showed that tuna eye oil and ICES30/4-enriched live food (4.83 ±1.29 and 4.61 ±0.99 mg g^-1 DW, respectively) showed the highest n-3 HUFA content for sturgeon fish larvae.

---

Advantages of pelleted feeds in terms of storage, transportation and lower costs compared to natural fresh feed justified the replacement of artificial feeds instead of natural ones partially on maturation performances. This study comprised nine treatments (with three replications) including control treatment: polychaete worm (Perinereis nuntia), Squid and calf liver (natural feed); T₁: pellet feed with 50% crude protein and 8% crude lipid+ Perinereis nuntia, Squid and calf liver; T₂: pellet feed with 50% crude protein and 10% crude lipid+ Perinereis nuntia, Squid and calf liver;  T₃: pellet feed with 40% crude protein and 10% crude lipid+ Perinereis nuntia, Squid and calf liver; T₄: pellet feed with 40% crude protein and 8% crude lipid+ Perinereis nuntia, Squid and calf liver Perinereis nuntia;  T₅: pellet feed with 50% crude protein and 10% crude lipid; T₆: pellet feed with 50% crude protein and 8% crude lipid; T₇: pellet feed with 40% crude protein and 10% crude lipid; T₈: pellet feed with 40% crude protein and 8% crude lipid. In treatments 1, 2, 3 and 4, 50% of the natural diets were removed and pellet foods used instead. The amount of pellet feeds that given daily, was 3.5% of shrimp broodstock biomass. In treatments 5, 6, 7 and 8, the amount of pellet feeds that given daily was 7.5% daily. Feeding was done 4 times a day. GSI in the control (3.23%), treatment 3 (3.20%) and treatment 6 (3.02%) were significantly higher than that in the other treatments (p<0.05). Absolute fecundity in the control (29980 eggs) and treatment 3 (29683 eggs) was significantly higher than other treatments (p<0.05). HSI reached the lowest level in treatment 8 (2.14%). But in treatments 3 and 5 was more than control, but did not any statistical significant (p>0.05). Survival rate in the treatment 8 (26.66%) was significantly lower than other treatments (p<0.05). Generally, In the treatment 3, with the elimination of 50% of the natural foods, and the use of pellet food instead of them, result of comparative indices of reproduction were in desirable proportions.

---

This study was carried out to evaluate the effect of different levels of garlic (Allium sativum) on growth survival and nutritional characteristics of goldfish (Carassius auratus). For this purpose, 180 goldfish with an average initial weight of 1.18± 0.08 g were introduced randomly into 12 aquaria (50×30×40 cm) in 4 groups, with 15 fish in each group. Treatments were fed on a basal diet for one week, followed by experimental diets for eight weeks. Garlic powder was added at levels of 0 (Control), 0.5, 1 and 1.5 mg kg^-1 to commercial diet. At the end of the experiment, growth and survival rates and feed performance were evaluated. There was no significant difference in growth rate and feed efficiency between treatments, although they were better in the 0.5% level. The highest survival rate was achieved in the 0.5% treatment that showed a significant difference compared to the control diet (p<0.05). The best growth performance and feed efficiency were obtained in fish fed the 0.5% garlic powder diet. 

---

This study evaluated the effects of diets containing various carbohydrate-to-lipid (CHO L^-1) ratios on growth performance, nutrient utilization body indices and hepatic lipogenic enzyme (malic enzyme, 6-phosphogluconate dehydrogenase and fatty acid synthase) activities. Triplicate groups of Pangasianodon hypophthalmus fingerlings were fed eight isoenergetic and isonitrogenous diets with different carbohydrate-to-lipid ratios (0.51, 0.79, 1.12, 1.79, 2.41, 3.24, 4.43 and 7.62). Higher body fat deposition and lower growth performance were observed in P. hypophthalmus fingerlings fed with high-lipid diet than those fed with high-carbohydrate diet. The fish fed the diet with 7.62 CHO L^-1 ratio exhibited significantly (p<0.05) higher hepatosomatic index compared to those fed higher lipid diets (0.51 and 0.79). High dietary carbohydrate level significantly increased (p<0.05) the activities of malic, 6-phosphogluconate dehydrogenase and fatty acid synthase enzyme. Based on the second-order polynomial regression analysis of weight gain, the optimal dietary carbohydrate and lipid contents for P. hypophthalmus fingerling were 304 and 103 g kg⁻¹, respectively, which correspond to a dietary CHO L^-1 ratio of 2.95.