<Original>Reproductive characteristics in captive Paradise fish Macropodus opercularis

[Synopsis] The Paradise fish, Macropodus opercularis, was categorized as an endangered species in Japan, and migrate from the northern part of Vietnam to the Ryukyu archipelago.As the ecological information on paradise fish was not investigated fully and the quantities are not sufficient enough to protect it. Reproductive characteristics were clarified by a breeding experiment to establish the artificial breeding technique for protection. The breeding trials were operated both outdoors and in the laboratory. During these trials, spawning was observed only in the case of one pair of broodstock fishes. A male and female were reared under constant environments (25.5±0.5℃, 14L–10D) to research the reproductive cycles. The number of the eggs was counted as in 165–356 (286±73, mean ±SD), and the diameter of the fertilized eggs measured 0.67±0.08mm (mean ± SD). Hatching was observed on the next day and the larvae proceeded to feed six days later. Each reproductive behavior was observed once per 20–39 days at least. The egg-mass after spawning and pre-larvae under a bubble nest were guarded by a male parent. Protective behavior was also found in females. However it was obstructed by a male who mistakenly perceived it as the enemy\u27s. The larvae leaving from the nest, were eaten by the female parents three days after hatching and the larvae started to be cannibalized by both parents