Induction of population triploid-interploid in rainbow trout (Oncorhynchus mikiss) using by indirect

Induced polyploidy is a suitable tool for producing sterile fish which made commercial benefits in the aquaculture industry. This study carried out in order to produce triploid-interploid population via mating tetraploid female with diploid male rainbow trout. Heat shock was used for making tetraploid population and the best temperature and induction time were examined. Result showed that highest mortality from 1 day after fertilization to emerging were in groups 6 of embryos (40.1%) and the lowest were in groups 3 (33 %). Flowcytometry results showed that some fish were polyploidy. Comparative analyze of genome levels in tetraploid fish to control fish (diploid) and hen as standard indicator, confirmed tetraploid fishes in this study. In conclusion we can state that heat shock induction for 7 minutes at 65 hour –degree after fertilization in 28ºC is optimum temperature for inducting tetraploid rainbow trout

Investigation of chromosome and ploidy levels of rainbow trout produced from imported eyed eggs

Rainbow trout is the main cultural species of coldwater fishes in iran. Often, aquaculturists intend to breeding in order to production of lines with higher growth rate potential and disease resistant. Nevertheless in the country, no trout breeding programs, has been performed yet and most of the farms focused on the cultivation of the first (unbred) race. While European countries progressed in trout breeding techniques and production lines with higher growth through genetic manipulation (chromosomal number and type changes of fish) and/or selection and their fish products derived from this technology, including eyed eggs and so on have sold to other regions of the world (eg: Iran). In this study, some biological parameters including survival, growth, feed conversion ratio (FCR.) and chromosomal number of two juvenile groups from imported( group 1) and native(group 2) eyed fish eggs were compared. For chromosomal investigation, blood smear test and flow cytometry were performed. sults showed a significant difference (P≤5%) in growth rate of native fishes and French group Native fish feed conversion ratio (0.9) was significantly difference (P≤5%) from that of French fishes (1.15). Chromosomal analysis showed no difference in chromosome number in treatments and two fish groups were 2n chromosome. Based on the results, the fishes of group 1 had faster grow potential and gain weight in less time than that of group 2 and this has been achieved to go through the process of selection and feminization without any change in number of ploidy. Whereas the ability of native fishes in food efficiency ( lower FCR.) was better. However, the reduction of rearing period is the benefit and preference of cultivation of imported or origionally foreign

Determination of suitable age and size for releasing of Salmo trutta caspius by evaluation of osmotic

This study was carried out to determine the appropriate size of Caspian trout (Salmo trutta caspius Kessler, 1877) juveniles for releasing to South Caspian Sea or possibility of cage culture in Caspian Sea water. 1611 specimens were exposed in 4 weight groups of 5, 10, 15 and 20 g, in 3 salinity trials: Caspian Water (11- 11.5), inshore water (7) and fresh water (control). Each trial was done in 3 replicates. The blood samples and tissue fixations carried out from juveniles of control group (in fresh water) and 3, 6, 12, 24, 72, 168, 240 hours after exposure of fish in different treatments. Plasma osmolal ity, Na^+ and Cl^- concentrations, were measured by osmometer, flame photometer, RA1000 respectively. Plasma cortisol level was determined by using RIA (radio immunochemical assay). Na^+, K^+-ATPase activity in homogenates of gills was estimated by phosphate released from ATP. Histological indicators including chloride cell diameter and nephron morphometric parameters were assessed using classic preparation and optic microscope with digital camera. Results of osmolality and ions measuring concurrently show that all weight groups can live in salinity of 7 and they maintain the osmolality and ion concentrations. In the Caspian water, weight groups excluding 5 g juveniles show same result. Mean plasma osmolality of 20, 15, 10 and 5 gr juveniles in control group (time of 0) were calculated 331.3±8.7, 307.7±6, 334.7±14.6 and 301±8.7 mosml/l. This parameter in the above weight groups after 240 hours exposure in the Caspian Sea water were measured 329±0.53, 321±9, 325.3±6.7 and 346.5±13.6 respectively. The observation of kidney glomeruli in histological sections shows that the diameter of glomeruli in 5, 10, 15 g weight groups in 7 and all groups in Caspian water decreased after 72 h adaptation period (p0.05) for 5g juveniles, whereas within weight groups of 10, 15 and 20 g in Caspian Sea water and groups of 15, 20 g in water of 7 salinity, the increase (p0.05), although in other groups, a significant increase of this parameter was detected during experiments. Na^+ ,K^+ -ATPase activity in juveniles of 5g weight group in 7 salinity and Caspian water was low (3.2 6.1 mol Pi /mg protein/ h). The enzyme activities in all weight groups were higher under the exposure in Caspian Sea water than that in water of 7 salinity. In group of 10 g juveniles at start time (control in freshwater) the activity of Na^+, K^+ -ATPase was significantly higher (p<0.05) than that in 20g group. It is may be related to some metabolic changes and transforming to parr-smolt