Effects of static magnetic field on hatching performance of kutum (Rutilus kutum)

A bioassay was conducted to investigate the effect of static magnetic field on hatching function of kutum (Rutilus kutum) in Veis incubators. For this purpose, three experimental treatments were conducted in triplicate with magnetic flux densities of 5, 15 and 25 milli-tesla along with control treatment (fish without exposed to the magnetic field). The obtained eggs from 8 female broodstock were randomly transferred to the incubators with density of 49,000 eggs in each incubator. Changes in water physicochemical parameters including water temperature, pH, dissolved oxygen, total hardness, nitrogen derivatives (ammonia and nitrite) and phosphate levels were daily evaluated during the incubation period. At the end of the incubation period, hatched larvae from each treatment were transferred to 100-liter Zug incubators without any magnetic exposure for monitoring their growth. The results of this study showed significant differences in total hardness, ammonia and dissolved oxygen concentration of water among the treatments (p<0.05). By considering the physiological characteristics of kutum, the best effect of static magnetic field was obtained in the 25 milli-tesla treatment. Besides, the number of hatched larvae in 25 milli-tesla treatment was significantly higher than the control treatment. However, there was no significant difference in the survival rate of larvae before yolk sac absorption among the experimental treatments (p>0.05). The results of this study showed that static magnetic field could have positive effects on water quality and survival rate of kutum larvae.