Spawning induction in doctor fish, Garra rufa (Heckel, 1843) by Ovaprim and captive rearing of larvae

The stimulatory effect of Ovaprim, a commercial spawning inducing agent consisting of salmon gonadotropin releasing analogue (GnRHa) and a dopamine D2- receptor antagonist, Domperidone, was studied in doctor fish, Garra rufa (Heckel, 1843) under hatchery conditions. The feeding and rearing condition effects on the survival rate of naturally produced larvae were also evaluated. Twenty-five fish were collected from Kohmareh stream (Helleh River), Fars province, Iran by electrofishing and transported to an ornamental fish hatchery. Fish were randomly divided into 5 groups and injected as follows: control fish received only 0.7% physiological saline (group 1) and groups 2 to 5 received 0.1, 0.2, 0.02 and 0.04 ml Ovaprim per fish. Six hours after injection, fish were evaluated for ovulation or spermiation success. None of the samples in control fish spawned until the end of experiment. Higher doses of agent in groups 2 and 3 caused a100% mortality in treated fish. In group 3, two males were spermiated but none of the females ovulated. In group 4, two ovulated fish were found whereas three fish died. Feeding larvae with newly hatched Artemia naupli and rearing in temperature close to 30ºC resulted in higher survival rate in comparison to fish fed a combination of phytoplankton and infusoria and compared to larvae kept in temperature lower than 24ºC or higher than 34ºC. In conclusion the results of this study showed that Ovaprim is effective in induction of spawning in doctor fish, but a dose much lower than those used in this study is recommended for use in hatchery to avoid brooders mortality. Feeding larvae with fresh Artemia naupli during weaning stage is also suggested for higher survival rate.