Document Type : Research Paper
Authors
1
Fisheries of Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran
2
Professor in Fisheries Department, Faculty of Natural Resources, University of Guilan, Sowmeh Sara, Iran.
3
Department of Fisheries and Aquatics, Mirzakochek Khan Fisheries Sciences and Industries Training Unit, Guilan Center, Agricultural Research, Education and Extension Organization Rasht, Iran.
4
Department of biology ,Faculty of Science, University of Guilan, Rasht, Iran.
10.22124/japb.2024.26682.1530
Abstract
Abstract:This study were conducted under three treatments and one control and each with 3 repetitions with designed biofilters containing a composition of bacteria (Bacillus, Corynebacterium, Nitrosomonas and Nitrobacter) with different concentrations and a control without bacteria for the biological treatment of glass tanks with a water volume of 0.4 cubic meters and a density of 10 pieces of great sturgeon fish fry (Huso huso) in each aquarium was done in the aquaculture hatchery of Mirzakochek Khan Training Center. The inlet water flow rate of each of the treatment and control breeding tanks was 0.004 liters per second and the number of water circulation times of each tank was determined once in 24 hours. After adding pool water and a species of great sturgeon (Huso huso) with an average weight (21.35 ± 2.67) to the glass tanks, feeding was done as usual with slight aeration and after 4 days a mixture of 4 bacteria in the form of thick suspensions with ratios of 105, 107, 109 cells per milliliter and no bacteria were added as a control to the biofilter that was placed at the outlet of these tanks and the amount of ammonia, nitrite and nitrate was measured weekly at different times. Once every week, the total weight of all 10 fingerling fish was recorded with a digital scale with an accuracy of 0.01 grams to evaluate the growth indicators of the fingerling fish. The results of 30 days of treatment with different concentrations of the candidate bacterial compound cultivated in biofilters showed a statistically significant difference in the water quality of the experimental and control treatments (P<0.05). During the test period, the amount of pH and oxygen, ammonia, nitrite and nitrate in the witness treatment showed an increasing trend, while this trend was decreasing in all three experimental treatments. Also, the growth indicators of great sturgeon fishes in breeding aquariums include: survival percentage, weight gain, specific growth coefficient in the experimental treatments compared to the control treatment, and on the contrary, the food conversion ratio in the control treatment was higher than the experimental treatments. This statistical difference between experimental and control treatments was significant (P<0.05). However, comparing the experimental treatments with each other, there is no statistically significant difference between them (P>0.05). Although the second treatment has a better condition than the other two treatments. Therefore, based on the results of this research, the candidate bacterial composition cultivated in biofilters with a concentration of 107 CFU/mL can be used to purify and improve the quality of the effluent of great sturgeon farms.
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