| Gobicypris rarus is a member of Cypriniformes order, Cyprinidae family, Gobiocypris genus. G rarus is a small freshwater fish which is endemic to China. It has many advantages including small size, fast sexual maturity, continuous spawning, annual reproduction, strong reproductive capacity, easy feeding, transparent egg membrane and so on. Therefore, G. rarus has been considered as a new experimental animal for artificial breeding and research. In recent years, due to the need of scientific research and the deluge of illegal electric fishing, the application of electricity in many aspects of fisheries is very common. How much impact will cause the fish resources by method electric fishing on earth, especially the impact on the gonadal development and reproduction offish, it is lack of relevant evidence at present, and there is not a clear statement. Under the condition of laboratory, we precede electrical stimulation on the larval and adult G. rarus, studied the effect of electrical stimulation on its juvenile growth, gonadal development, reproduction after sexual maturity and reproduction of adult fish. The main contents are as follows:1. The larval G rarus of one month with initial body length of 1.02 ± 0.12cm, weight of 0.018±0.001 g were randomly divided into five groups, which were control group, one-time electrical stimulation group, three-time electrical stimulation group, five-time electrical stimulation group, and continuous electrical stimulation group. It was being electrical stimulation one times every five days. Each group has eighty-five larval fish. The experiment was end after the observation of reproduction. The results showed that:(1) The proper cyclical electrical stimulation could promote the growth of G Rarus larvae. But the rate of growth slows down approaching sexual maturity, and the control group had no significant difference. and the continuous cyclical electrical stimulation had no effect on male G rarus larvae. The effect on the growth of male with continuous cyclical electrical stimulation was changing firstly restraining after promoting by the increasing of electrical stimulation times. The result shows that it had no effect on the growth of male. Similarly, the effect on the growth of female with continuous cyclical electrical stimulation was also changing firstly restraining after promoting by the increasing of electrical stimulation times. The result shows that it had significant difference on the growth of female (P<0.05), and restrained the growth of female G rarus larvae.(2) The proper cyclical electrical stimulation could promote the gonadal development of G rarus larvae, and the continuous cyclical electrical stimulation had no effect on male G rarus larvae, but restrained the gonadal development of female G rarus larvae.(3) The proper cyclical electrical stimulation had no effect on the reproduction after reaching sexual maturity of G rarus larvae, and the continuous cyclical electrical stimulation had no effect on the reproduction after reaching sexual maturity of male G rarus larvae but caused female un-spawned or laying of white color eggs. The spawned female significantly prolonged the spawning period to 4.5 days (P<0.01), and the egg laying amount was significantly decreased to 36 (P<0.01), and the fertilization rate of male individuals significantly increased by 9.2 percent (P<0.05)as well.(4) Using histological method, proper cyclical electrical stimulation had no effect on the female ovary and the male testis after reaching sexual maturity of G rarus larvae, and the continuous cyclical electrical stimulation injured the large egg cell of female ovary after reaching sexual maturity of G rarus larvae. But there was no effect on the testis of male in histology for the electrical stimulation.(5) It had no effect of electrical stimulation on the body length and weight of first filial generation of G Rarus larvae after sexual maturity.2. The sexual maturity female G rarus with body length of 3.58 ± 0.22cm, weight of 0.575 ± 0.023g, and the sexual maturity male G rarus with body length of 3.26±0.24cm, weight of 0.418±0.039g were divided into four groups, which were control group, one-time electrical stimulation group, three-time electrical stimulation group, and five-time electrical stimulation group. It was being electrical stimulation one times every day. Each group has six pairs sexual maturity fish, and make a pair with the ratio of 1:1 respectively. The experiment was end after the observation of reproduction. The results showed that:(1) The electrical stimulation caused females un-spawned or laying of white color eggs. Electrical stimulation of three times significantly decreased the egg laying amount to 74 (P<0.05). Electrical stimulation of five times significantly prolonged the spawning period to 10.2 days (P<0.05), and the egg laying amount was significantly decreased to 80 (P<0.05) as well. Electrical stimulation of one time caused the fertilization rate of male individuals significantly increased by 15 percent (P<0.05).(2) Using histological method, varying degree of damage on the ovary was observed, and more stimulation times given, more damage was detected. But there was no effect on the testis of male in histology for the electrical stimulation.(3) It had no effect of electrical stimulation on the body length and weight of first filial generation of G. rarus. |
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