Journal of Aquaculture Development
Year:2015 | Volume:9 | Issue:3|Papers Count:8

This study aimed to determine the best method of diet changes for pike perch fingerlings from natural diet to commercial feed. We used 36-days pike perch fingerlings with mean initial weight 1.6±0.07 gr. Juveniles were introduced to nursery ponds four treatments including: treatment 1: artificial diet, treatment 2: chironomid+ artificial diet, treatment 3: tubifex worm+ artificial diet and treatment 4: mixture of chironomid and tubifex+artificial diet. Changing adaptation method from live food to commercial food conducted by decreasing proportion of live food and increasing commercial food ratio. The experiment duration was21 days and fingerlings in all treatments fed by commercial diet from day 19. According to the results, the highest rate of weight gain (mean: 0.49±0.72gr), average daily growth (0.023±0.034 gr), specific growth rate (mean: 1.03±1.47) and condition factor (mean: 0.69±0.24), belonged to treatment 4. Data of tukey test indicated that all growth indices, except condition factor, had significant difference between treatment 1 with 3 and 4, as well as, treatment 2 with 3 and 4 (p<0.05). A significant difference of condition factor observed between treatment 4 with 1 and 2 (p<0.05). There was no significant difference in the survival and cannibalism rate. The results totally showed that the best method for diet changes of pike perch fingerlings to commercial food can be a combination of two or more live foods because pike perch fingerlings adapt to the food variation and will accept artificial food better.

In order to evaluate integrated culture of fish and rice on rice yield and soil nutrients availability, an experiment has been done on the crop year of 1391 [2012] in nine rice fields of some cities such as Astaneh Ashrafieh, Talesh and Asalem, all in Guilan Province, Iran. The fish were released after the preparation of the field when the water level reached about 15 cm. The normal occupations have been done by the farmers in the local conditions. A plot of land by the area of 100 square meters was considered as control plots; however, the fish were not in the control fields. Sampling soil and plant has been done in the harvest time. The dry weight of shoot, height and grain yield was measured. Nitrogen, phosphorus and potassium availability and its uptake by plant were also measured. The results of t-test analysis showed that there is a significant increase in availability N, P and K in fishrice cultivation than in the control (rice cultivation, alone) in 5% level. The yield of plant increased in comparison with control and the uptake of N, P and K by in fish-rice cultivation increased than in the control, significantly.

Phylogenetic relationship of two economical valuable species from genus Rutilus of cyprinids including Caspian Kutum (Rutilus frisii kutum) and Caspian roach (Rutilus rutilus caspicus), to investigate the sister relationship in Southern of Caspian Sea were compared. After Fin clip samples collection, extraction of DNA, PCR and DNA sequencing were carried out then by partial mitochondrial cytochrome b gene based on DNA sequencing method. To analysis some of diversity indexes, Phylogenetic relationships using neighbor-joining (maximum-likelihood model) and maximum parsimony (1000 bootstrap replicates) were measured. 14 haplotypes were obtained, haplotype diversity between two species was 0.761, 114 variable sites were obtained in all sequences. The average genetic distance of two sub-species was 0.09.In phylogenetic relationships trees drawn two species were on separate clades. The results of this study showed that genetic diversity among two species is high and there is no distinct sister-clade.

Presenting the new methods and producing the new food supplements could have effects on efficiency and sustainable development on Ornamental fish breeding as an important sector of aquaculture. In the this study, the effect of ethanolic extract of F.vulgar having phytoestrogen compounds on growth performance and fertility rate of Guppy was tested for offering it as a food supplement in the aquaculture. 360 Juvenile guppies were distributed into 12 glass aquaria at 30 fish/ tank in triplicate. Four diets containing varying levels of alcoholic extract of fennel seed at 0. 75, 100, 125 m/ g were prepared and fed to the fish twice a day at 3% of their body weight. The results for each group were compared statistically with those for the control. Analysis of the results showed a significant increase in weight gain and fertility rate in group T2 (100ml/g). The increase in fertility rate in tests groups may be due to the increase in the level of estrogenic compound which in turn could be due to the action of the extract present in the diet. The observation made in the present investigation show that F.vulgar can act as a phytoestrogenic compound at low concentration and, hence, F. vulgar can be considered as a potential as well as a natural additive to fish feed in commercial aquaculture to augment the fertility rate.

This study has been carried out to investigate the effects of physicochemical parameters on growth indices of Litopenaeus vannamei shrimp in six earthen ponds (1.5, 2 and 2.5 hectares) with stocking density of 30 ind/m2 and the same releasing time in Gomishan shrimp farm sites (Golestan province) during 140 days from May to September in 2013. The results showed that some parameters such as salinity and transparency were out of optimum range for L. vannamei. The highest final weight for the studied shrimps observed in 2.5 ha ponds. The lowest SGR (specific growth rate), and FCR (food conversation rate) observed in 1.5 ha pond (1.75±0.01) and in 2 ha pond (1.27±0.01) and the highest mean survival rate (85.8±14.4) was due to 1.5 ha ponds. However, it seemed that the shrimp culture is justified in pools 2.5 hectare for higher food conversation rate, lower survival rate but higher growth performance rate and body weight.

This study has conducted to measure concentrations of heavy metal including Pb, cd, Zn,and Cu in muscle, and liver tissues of Liza aurata along Kiashar and Talesh region of southern coast of Caspian Sea .In 2007 the muscle and liver tissues of 28 fish sample (14 in each region) removed, digested in acid mixture and concentrations of mentioned heavy metals determined by flame atomic absorption. Average concentration of Pb, Cd, Zn, and Cu in muscle were 1.441±0.063, 0.109±0.024, 31.08±6.51, 2.524±0.748 and in liver were 1.953±0.124, 0.196±0.015, 33.021±4.24, and 4.288±1.039 ppm dry weight respectively. The concentration of Pb and Cd were higher in Kiashar than in Talesh region while the level of Zn and Cu were higher in Talesh. The result showed that the accumulation of heavy metals were highest in liver tissue than muscle in both regions.

Origanum vulgare is member of the mint family that in traditional medicine has been used as a reducing menstrual problem. This study compared the effects of hydro alcoholic extract of air branch of Origanum vulgare, LHRH-A2, and 17β-estradiol on ovarian tissue of immature Trichogaster trichopterus. 150 individual of three spotted gourami (Trichogaster trichopterus) by the average weight of 2.1 ± 1 g evaluated. Samples of 10 fish in each experimental group were distributed into 12 treatments and three controls. Four doses of Origanum vulgare and 17b-estradiol (10, 20, 30, and 50 mg/kg fish body weight) and 4 doses of LHRH-A2 (0.001, 0.002, 0.003 and 0.005 mg/kg fish body weight) were exposed in 12 experimental groups. There were three control treatments: saline, ethanol and placebo. Injections were intramuscular, one dose every other day and seven doses in total. Mean of gonad osomatic index (%) and histological structures of ovary in all treatments measured and compared with the controls. The results of the statistical analyses of gonad osomatic index showed there are significant difference between the three treatments control and experimental groups (P£0.05). Investigation showed that a dose of 50 mg/ kg, after 17b-estradiol treatment, Origanum vulgare accelerated oocyte maturation in Trichogaster trichopterus. Also the results of histological structures and oocyte diameter confirmed Gonad osomatic index. The findings of study showed that extracts of Origanum vulgare dose-dependently affect oocyte maturation in Trichogaster trichopterus.

The feeding habits of striped piggy (Pomadasys stridens) was studied in Bushehr waters of the Persian Gulf. The sampling was done monthly over a 12-month period from January 2012 to December 2013. W_L relation, type of feeding, frequency of prey (FP), Gastrsomatic Index (GaSI) and vacuity index of 468 fish statistically compared bt ANOVA.W-L relation showed that there is an egative allometric growth model.t pauly showed that it has a significant difference between estimated value (2.48)and predicted (3)(P>0.05). The length weight relationship for this species were estimated as W= 0.00754FL 2.48. In total, seven items were found in the stomach of this species. The maximum gastro-somatic index (GaSI) was measured during May (94.0%) and February (93.0%) while the minimum was measured November (26.0%) and December (23.0%). The maximum value of the index of vacuity (CV) was measured during February, while the minimum value was measured during November and December. The estimated FP for crustaceans and mollusks showed as main items (FP ³ 50), Nematodes and Foraminifera as secondary items (10 %< FP<50%). In overall, the results show that this fish is a relatively predator species which consume mollusks and crustaceans as a major food.