An investigation on the sustained releasing delivery of GnRHa using Freund's incomplete adjuvant in rainbow trout (Oncorhynchus mykiss)

In this study, Freund's incomplete adjuvant (FIA) was used for emulsifying and sustained releasing of gonadotropin releasing hormone agonist (GnRHa) in Rainbow trout (Oncorhynchus mykiss). The hormone [D-Ala6, des GlylO] m GnRHa was diluted in 0.25ml physiological saline and mixed with equal volume of FIA (GnRHa-FIA). A group of Rainbow trout broodstock were injected with GnRHa-FIA and compared with those receiving the treatment in two steps or one acute GnRHa injection. All of the fish that received GnRHa in emulsified form or in two steps injection ovulated in 10 and 11 days after injection respectively. In contrast, only 75% of the control fish and 60% of the fish with an acute injection ovulated up to 36 days after injection

Assessment of digestive enzymes activity during the fry development of rainbow trout, Oncorhynchus mykiss: from hatching to primary stages after yolk sac absorption

The aim of this study was to determine the activity of digestive enzymes during the fry development of Rainbow trout ( Oncorhynchus mykiss ), which has a remarkable role in food digestion and absorption in the first feeding. The assessment of digestive enzymes activity of gastric (pepsin), pancreatic (trypsin, chymotrypsin, α-amylase and lipase) and intestinal (alkaline phosphatase) revealed that enzymes were available on the first day after hatching (DAH) but their activity showed no significant difference from hatching to day 12 (P > 0.05). An increased activity was seen between 12 and 18 DAH and this activity was significantly higher than the first 12 days (P 0.05). These results could be used as a basis for formulating a suitable feeding and also selecting the best time for starting the feeding so that optimum nutritional values and cost-effectiveness are achieved

In vitro inhibition of growth in Saprolegnia sp. isolated from the eggs of Persian sturgeon Acipenser persicus (Pisces: Acipenseriformes) by Pseudomonas aeroginosa (PTCC:1430)

Saprolegnia is one of the most important agents decreasing the eggs survival rate in sturgeon hatcheries.There are some chemical substances for controlling the fungal infection of eggs. In this study, an attempt was made to introduce a germ negative bacterium, Pseudomonas aeroginosa (PTCC1430)(Persian Type Culture Collection) as a biocontrolling agent of water mold. Saprolegnia was isolated from the eggs of some infected Persian sturgeon, Acipenser persicus in a sturgeon hatchery and then was purified. P.aeroginosa was cultured in Potato dextrose Agar (PDB) media and then was prepared in 5 concentrations (103,104,105,106and107cfu.ml-1) while challenging with fungi in petri dishes under laboratory conditions.The results showed that by increasing the concentration of the bacteria in plates, hyphal growth of the fungi was reduced. The highest concentration of P. aeroginosa concentration (107) roughly stopped the -fungi growth and the Minimum Inhibitory Concentration (MIC) was 104cfu.m-l. Results in this study implied the potential of P. aeroginosa (PTCC1430) as a biological agent in controlling saprolegniosis

Changes in biochemical and physiological responses of common carp, Cyprinus carpio L. after long-term exposure to Pb (II)

In this study, the chronic toxic effects of Pb (II) on common carp, Cyprius carpio were investigated using several biomarkers at different levels of biological functions for assessing changes in ecosystem quality. In a bioassay,common carp juveniles were individually exposed to different dose of heavy metal, Pb II (0, 0.45, 0.89, 1.34 mg.l-1) for 28 days. Morphological indices such as hepatosomatic index, condition factor and lipid peroxidation (LPO) level and also the activities of superoxide dismutase (SOD) and catalase (CAT) were measured. These results indicated that there was significant lower condition factor in fish exposed to the highest concentration of Pb (p<0.05). The activity of hepatic antioxidant enzymes (SOD & CAT) and LPO level was significantly elevated after long-term exposure to higher concentration of Pb (p<0.05). Briefly, our findings suggested that common carp exposed to lead, develop oxidative stress, hence long-term exposure to higher concentrations of Pb could seriously affect the health status of fish

Effects of Diazinon concentrations on LC50, hematocrit and clinical signs of Roach Torkemani (Rutilus rutilus caspius) fries of Caspian Sea

Effects of different concentrations of Diazinon on Roach Torkemani (Rutilus rutilus caspius) fries supplied from Ghareh-Soo Fishery Research Station was studied in Gorgan University of Agricultural Science and Natural Resources in 2009 to determine 50% lethal concentration (LC50) for the fish within 96 hours. In this study, 126 Roach fries with mean weight of 3 grams were used. Tests were performed statically based on instructions of O.E.C.D under fixed water quality conditions at the temperature 24±1 and pH 8-8.5 in a completely random trial with five concentrations treatments of Diazinon (5, 5.95, 7.07, 8.48 and 10mg/l) in three replications and the means were compared using Duncan test at 5% significance level. The results indicated that at the end of 96-hour test, LC50 was 7.88mg/l. In this test, clinical signs such as hunched spinal column, thrilling, clot in caudal fin and head, and irregular swimming were observed in the studied fish specimens. In hematological examination, there was a remarkable decrease in percent of hematocrit between concentrations of 5 and 5.95mg/l of Diazinon. By increasing the concentration of this poison, the decrease became slower.Furthermore, there was a significant difference in percent of hematocrit between control group and LC50 group, with mean amounts of 36 and 27%, respectively. Based on the results, Diazinon was classified as toxic pesticide for Roach Torkemani

Infection of three-spined stickleback Gasterosteus aculeatus (L.) with Corynosoma strumosum in Gomishan Lagoon

To study infection of Three-Spined Stickleback, Gasterosteus aculeatus (14 we sampled 530 specimens of the fish during November 2000 till October 2001 in Gomishan Lagoon, southeast of Caspian Sea. The fish were collected using beach seines with 3mm mesh size. The specimens were transferred to lab fresh or fixed in 10% formalin and examined by standard methods. Numbers of parasites for each male or female were recorded and intensity, frequency and prevalence of the parasite for each month and sex were calculated. Maximum infection occurred in late winter and early spring and the maximum number of parasites was 82, obtained from a female fish in early spring

Effect of parasite infection with Posthodiplostomum cuticola (Nordmann, 1832) on fish growth rate in Zaringol Stream in Golestan Province

This study investigated the effect of parasite infection with Posthodiplostomum cuticola on fish growth rate in Zaringol Stream in Golestan Province. A total number of 447 fish specimens (173 Capoeta capoeta gracilis, 111 Alburnoides eichwaldii, 131 Paracobitis malapterura, 32 Neogobius fluviatilis) were captured by electrofishing during December 2009 to September 2010. Total number of parasite on fish body was counted by investigating internal organ and surface of skin and branch. Results showed that slope of regression curves and condition factor were significantly lower in infected C. c. gracilis. N. fluviatilis was the most abundant infected fish in Zarringol Stream. It seems that it's feeding dependence on benthos makes this fish more susceptible to infection by parasite

Comparison of digestive enzyme activity in the stomach, pyloric caeca and intestine in diploid and triploid female of rainbow trout (Oncorhynchus mykiss)

The effects of chromosome manipulation on the digestive enzyme activity in the rainbow trout were studied. The enzymes included Pepsin, Trypsin, Chymotrypsin, cileimylase, Lipase and Alkaline Phosphatase which were assessed in diploid and triploid female of rainbow trout. Pepsin activity in the stomach of the assessed fish showed no significant difference between the diploid and triploid fish (P>0.05). The measurement of Trypsin and Chymotrypsin activity in the intestine and pyloric caeca revealed no significant difference in the treated and untreated fish (P>0.05). The activity of a-Amylase, Lipase and Alkaline Phosphatase showed no significant difference in the intestine and pyloric caeca of the diploid and triploid fish (P>0.05).The results indicated that chromosome manipulation in rainbow trout had no effects on digestive enzyme activity

Effects of gradual salinity increase on osmoregulation in Caspian roach Rutilus caspicus

This study was carried out to determine the effects of gradual salinity increase on osmoregulatory ability of the Caspian roach Rutilus caspicus, under conditions which mimic stocking conditions of hatchery-raised fish. Initially, 30 juvenile fish (mean ±s.d. 3·20 ± 0·34 g) were transferred to 20 l circular tanks, in which salinities were changed in a stepwise fashion, from 0 to 5, 10 or 15 at 48 h intervals. The fish at salinity 15 were held for an additional 48 h at this salinity. Forty-eight hours after salinity transfer, survival rate, haematocrit, plasma Cl⁻, Na⁺ and K⁺ concentrations, osmolality and gill Na⁺/K⁺-ATPase (NKA) activity were measured. The only effect of exposure to 5 was a significant reduction in haematocrit compared to the freshwater control group. Exposure to salinity 10 raised haematocrit, Cl⁻ and Na⁺ concentrations and osmolality. At 48 h exposure to salinity 15, haematocrit, Cl⁻ and Na⁺ concentrations and osmolality were significantly higher than freshwater controls, and gill NKA activity was significantly lower, but the effect on NKA was no longer evident at 96 h exposure. There were no effects on survival. These results indicate that R. caspicus juveniles experience an initial non-lethal iono-osmotic perturbation following salinity increase but can adapt to brackish water at salinity 15. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles

Survey on parasite infection of two years old carp bream, Abramis brama, to Ligula intestinalis in Alagol lake and Gorganroud (Golestan dam) - Golestan province

To evaluate the infection of carp bream (Abramis brama) with ligula intestinalis in Golestan province, 92 fish samples from two regions: Gorganroud (61 samples) and Alagol lakes (31 samples) were investigated. According to the result in the present study, the prevalence of ligula intestinalis plerocercoid infestation in carp bream from Alagol Lake for male, female and overall (male and female) were 5.88%, 7.14% and 6.45%, respectively, also in the Gorganroud river for male, female and overall (male and female) were recorded as 22.22%, 26.47%, and 24.59%, respectively. Based on the statistical analysis, the prevalence of this parasite in fish specimens from the Gorganroud was recorded significantly higher than Alagol lake`s specimens. In this study, the mean intensity ± SD of parasite infestation for carp beam in Alagol Lakes and Gorganroud were recorded as 2.5 ± 2.1 and 2.00 ± 1.25, respectively. There was no significant difference in mean intensity of ligula intestinalis infection between two mentioned regions (P<0.05). The length of isolated and number of isolated parasites for each infected fish was different between 6 -64 cm and 1-5 numbers respectively. Totally, mean prevalence and intensity of ligula intestinalis infection for both regions in Golestan province were recorded as: 18.48 % and 2.05 ± 1.25 number (per infected fish) respectively. There was no significant difference between male and female for prevalence and intensity of parasite infection in this study (P<0.05)