USE OF THE ROTIFER, BRACHIONUS-CALYCIFLORUS PALLAS, IN FRESH-WATER ORNAMENTAL FISH LARVICULTURE

The Brachionus calyciflorus used in this study were produced by batch culture using Chlorella spp. as feed. Larviculture experiments in indo or 10-1 and 200-1 tanks revealed that, compared with egg yolk, the rot ifers used as starter food significantly improved the growth and survi val of Dwarf Gourami larvae (Day 2-12). These beneficial effects also extended to the subsequent Artemia feeding phase (Day 13-32), suggesti ng that the quality of starter food is crucial to later development. A t metamorphosis, the overall survival rate of larvae fed on rotifers i n indoor tanks (65.1-74.5%) was about four times of that obtained in e xtensive culture in open ponds (17.5%). In Discus, larvae are dependen t on the body slime of their parent as a nutrient during the first two weeks of exogenous feeding. Our observation demonstrated that Brown D iscus larvae could be raised in the absence of the parent fish by usin g rotifers as starter food followed by Artemia nauplii. Their growth a nd survival. rate were comparable to those on parental feeding. The ar tificial feeding would eliminate the risk of larvae being eaten by the parent fish and shorten the brooding interval of the spawners, thereb y leading to higher yield of fry. This feeding protocol is less tediou s 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.