The effects of different hormone administration methods on propagation successes in African catfish (Clarias gariepinus)

Successful propagation of fish depends on many factors including the optimal administration routes and delivery vehicles of spawning agents. In our experiments, the effects of different routes of administration and delivery vehicles of Ovopel (mammalian GnRH-analouge and metoclopramide) on ovulation were compared in African catfish (Clarias gariepinus). Seven females per treatment were used (BW = 606–1088 g). In experiment 1, fish in treatment 1 and 2 were given intramuscular (IM) and intraperitoneal injections (IP) of Ovopel suspended in fish physiological saline, respectively. For treatment 3 and 4, Ovopel was suspended in fish physiological saline (NaCl) and fish sperm (SP), respectively. The suspensions were introduced into the ovary of the females by a catheter. In experiment 2 (verification or clarification experiment), two treatments were administrated identically as experiment 1 for IM and SP. As a new treatment (SI) sperm was introduced into the ovary by a catheter, the Ovopel were administrated intramusculary. In both experiments, all females ovulated in all treatment groups. The relative number of stripped eggs was also similar among treatments within experimental cycles. Hatching rate was significantly lower for treatments where fish sperm was introduced to the ovary by a catheter whether it contained Ovopel (39.1 ± 18.3 %; SP, experiment 1 and 35.1 ± 21.2 %; SP, experiment 2.) or not (SI: 46.0 ± 9.2 %). While in other treatments, hatching rates were significantly higher and varied between 55.1 ± 16.1 % (IM), 66.7 ± 9.3 % (IP), and 63.4 ± 9.0 % (NaCl) in experiment 1 and 61.9 ± 12.0 % (IM) in experiment 2. The result of ovarian lavage with hormone preparations in saline have shown that the effects this novel method do not differ from the effects of reproduction with the use of traditionally injection by needle.