The Israeli Journal of Aquaculture - Bamidgeh 51(1), 1999, 26-39.


S. Rothbard, I. Rubinshtein, L. David

YAFIT (R&D) Laboratory. Fish Breeding Center, Gan Shmuel 38810, Israel

W. L. Shelton

Zoology Department, University of Oklahoma, Norman, OK 73019, USA

Androgenesis in Japanese ornamental (Koi) carp was induced in batches of Yugoslavian common (mirror scaled) carp eggs. Eggs were immersed in a synthetic (SOF) or carp natural (cNOF) ovarian fluid and placed in Petri dishes on a rotating shaker (60 rpm) during irradiation with a UV dose of 2000, 2500 or 3000 J/m². The treated eggs were fertilized with koi sperm and the paternal genome was diploidized by heat (4010 C/2 min) or pressure shock (7500 psi/2 min), during the first mitotic division. The highest yields (7.8%) of androgenetic hatched larvae (androgenotes), indicated by a paternal color marker (lack of melanophores), were obtained in batches heat-shocked at the embryonic age of t=I.5t0. Eggs irradiated in cNOF showed two to three-fold higher survival than eggs irradiated in SOF. The extremely low survival of androgenotes in all experiments can be attributed to loss of viability from irradiation or elevated mortality from shock treatments and greater likelihood of homozygous mutation, in two preliminary trials, batches of koi and carp eggs (15,000 and 17,000, respectively) were activated with Yugoslavian (mirror) carp or koi (fully scaled) sperm respectively, and diploldized by late cold shock (2-41C/45 min). The female carp X male koi group yielded 17 androgenetic larvae, recognized by the color marker. No androgenotes hatched from the reciprocal group (female koi x male carp). All putative androgenetic offspring, that carried the paternal (mirror scalation, were examined at the size of 3-5 cm and were found to be fully scaled, Indicating hybrids rather than androgenotes. Further examination of cold-shock induction is planned. It is recommended that further experiments be conducted to optimize the method.