Fisheries
Abdoljabbar Irani
Abstract
In this study, rainbow trout diploid, triploid, and tetraploid were comparatively investigated regarding the growth performance, survival rate, and erythrocyte characteristics. For the triploid production, the fertilized eggs received 26.5 ℃ thermal shock under three treatments: 1. double ...
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In this study, rainbow trout diploid, triploid, and tetraploid were comparatively investigated regarding the growth performance, survival rate, and erythrocyte characteristics. For the triploid production, the fertilized eggs received 26.5 ℃ thermal shock under three treatments: 1. double 1-min shock after 15 and 30 min of the fertilization, 2. one 15-min shock after 15 min of the fertilization, and 3. one 12-min shock after 20 min of the fertilization. Tetraploidy was induced by application of 28 ℃ thermal shock under three treatments: 1. 10-min shock after 59 degree-hours of the fertilization, 2. 10-min shock after 66 degree-hours of the fertilization, and 3. 10-min shock after 72 degree-hours of the fertilization. The best triploidization results, 66.6% survival rate and 87% triploidization rate, achieved by application of 12-min shock after 20 min of the fertilization. The best tetraploidization results, 54.9% survival rate and 7.94% triploidization rate, achieved by application of 10-min shock after 59 degree-hours of the fertilization. There were no significant differences between the triploid and diploid fish, wheras the tetraploids showed significantly lower growth rate than the diploids. In conclusion, in this study, triploid and tetraploid production of rainbow trout were improved, and application of erythrocyte cell size as a reliable and efficient polyploidy detection method was emphasized.
Abdoljabbar Irani*; Abdolmajid Hajimoradlo; Naser Agh; Rasul Ghorbani
Volume 5, Issue 3 , March 2017, , Pages 79-106
Abstract
Nitrification rate of biofilters is influenced by ammonia concentration and levels of ammonia vary in response to feeding time. On the other hand, existence and activity of different groups of bacteria can be expected in the biofilters. Hence in this research, nitrification dynamic of biofilters during ...
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Nitrification rate of biofilters is influenced by ammonia concentration and levels of ammonia vary in response to feeding time. On the other hand, existence and activity of different groups of bacteria can be expected in the biofilters. Hence in this research, nitrification dynamic of biofilters during day hours and also rules of different biofilteration process (nitrification, denitrification and anamox) in aerobic biofilters of Common carp recirculating aquaculture system were surveyed. To conduct of this research 12 pilot recirculating aquaculture systems with barley straw, wood chip, sponge and PVC pure pipe based biofilters were designed. After activation of biofilters, nitrification rates measured at day 46 and 61 in 4 hour interval and via sampling of granules from biofilters at day 62, nitrification, denitrification and anamox process were surveyed. Results indicated that nitrification rates were different during day hours, as so peak rates observed in related to feeding time. Nitrification rates in batch culture of granules were greater than maximum rates obtained for biofilters established in recirculating aquaculture systems and these granules showed not only nitrification but also denitrification and relatively anamox activities. In conclude by modifying the management of biobilters all biofilteration process of inorganic nitrogen wastes can be useful.
