Early development and growth of the eastern rainbowfish, Melanotaenia splendida splendida (Peters). I. Morphogenesis and ontogeny

Abstract

This paper describes the ontogeny and morphogenesis of the eastern rainbowfish, Melanotaenia splendida splendida, including details on reproduction and the conditions required for laboratory breeding and rearing. M. s. splendida is easily bred under standard laboratory conditions using readily available commercial foods. Aquaria with two males and three females can produce between 40 and 200 eggs daily. They can be induced to spawn daily throughout the year through manipulation of light and temperature conditions. The eggs, which ranged in size from 0.93 to 1.20 mm, had a homogeneous yolk and a clear, uniform chorion, making observation of developmental stages possible. Development was telolecithical and division was meroblastic. Development of M. s. splendida was similar to that of other Melanotaenia species. At 28°C, hatching occurred between 4 and 8 days, with an average larval length of 3.7 mm standard length. Growth was rapid and the fish reached sexual maturity within approximately 90 days. Knowledge of the developmental stages of M. s. splendida is important in enabling further work, such as bioassays and environmental monitoring, to be carried out, investigating the ways in which changes in the environment, such as pollution, will impact on Australia's freshwater fishes. Melanotaenia splendida splendida is an ideal species for this purpose in the north-eastern tropics of Australia.