Use of a novel induced spawning technique for the first reported captive spawning of Tetraodon nigroviridis

The spotted green pufferfish (Tetraodon nigroviridis) is an important genetics model animal due to its small, well-mapped genome. However, only wild-caught juveniles and adults are available to researchers. A lack of gametes, fertilized eggs, developing embryos, and other early life stages hampers development of the full potential of T. nigroviridis as a model research species. We report on successful spawning trials using a novel induced spawning technique, ovarian lavage. Chorulon^® (human chorionic gonadotropin, hCG) was injected into a catheter inserted into the oviduct at a rate of 3 μl/g body weight. In one trial, a female paired with a male spawned in an aquarium at about 72 h post-treatment. In other trials, females were hand-stripped of eggs at 36 h post-treatment. There were 3680 eggs/g of eggs and females produced up to 24% of their body weight in eggs. Hatch resulted from all trials on the 4th day post-fertilization. Ovarian lavage is a simple method for administering spawning hormones, uses a catheter technique similar to that frequently performed to determine egg maturity in broodstock, and eliminates the need for injection.