The Brachionus calyciflorus used in this study were produced by batch culture using Chlorella spp. as feed. Larviculture experiments in indoor 10-1 and 200-1 tanks revealed that, compared with egg yolk, the rotifers used as starter food significantly improved the growth and survival of Dwarf Gourami larvae (Day 2-12). These beneficial effects also extended to the subsequent Artemia feeding phase (Day 13-32), suggesting that the quality of starter food is crucial to later development. At metamorphosis, the overall survival rate of larvae fed on rotifers in indoor tanks (65.1-74.5%) was about four times of that obtained in extensive culture in open ponds (17.5%). In Discus, larvae are dependent on the body slime of their parent as a nutrient during the first two weeks of exogenous feeding. Our observation demonstrated that Brown Discus larvae could be raised in the absence of the parent fish by using rotifers as starter food followed by Artemia nauplii. Their growth and survival rate were comparable to those on parental feeding. The artificial feeding would eliminate the risk of larvae being eaten by the parent fish and shorten the brooding interval of the spawners, thereby leading to higher yield of fry. This feeding protocol is less tedious and more practical for use in commercial farming of Discus than the existing strategies of smuggling the batch of larvae to foster parents or feeding the larvae with egg food. The use of rotifers would enable freshwater larviculture to improve larval performance, increase yield, and facilitate breeding of new fish species with small larvae.
(Primary Prod. Dept., Sembawang Field Expt. Stn., Ornamental Fish Sect., 17 km Sembawang Rd., Singapore 769194, Singapore)
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