Induced ovulation and spawning of cultured freshwater fish in China: Advances in application of GnRH analogues and dopamine antagonists

The Linpe method of induced ovulations and/or spawning of cultured fish consists of treatment with an analogue of gonadotropin-releasing hormone (GnRH) plus a dopamine antagonist. Initial experiments on common carp, silver carp, mud carp, bream, grass carp, bighead carp, black carp and loach confirm that ovulation can be induced in each of these species by injection of pimozide or domperidone plus [D-Ala6, Pro9 NEt]-luteinizing hormone-releasing hormone (LHRH-A) or [D-Arg6, Trp7, Leu8, Pro9 NEt-]-LHRH (sGnRH-A). Domperidone and sGnRH-A are preferred because of higher potencies in several species, allowing for their use at low dosages. For most species one set of simultaneous injections of the two drugs has proven sufficient to induce a high rate of ovulation within a predictable period of time. Ovulations are complete and ovulated eggs have been shown to be fertile. Hatching rates and fry survival are as high as high as with traditional methods of induced spawning. Subsequent reproductive cycles appear not to be altered by induced ovulation with the Linpe method. Although some refinement of dosages of drugs is required, the Linpe method has proven to be a highly successful procedure for induced ovulation and/or spawning of cultured freshwater fish in China.