Use of the rotifer, Brachionus calyciflorus Pallas, in freshwater ornamental fish larviculture

The Brachionus calyciflorus used in this study were produced by batchculture using Chlorella spp. as feed. Larviculture experiments in indoor10-l and 200-l tanks revealed that, compared with egg yolk, the rotifersused as starter food significantly improved the growth and survival of DwarfGourami larvae (Day 2–12). These beneficial effects also extended tothe subsequent Artemia feeding phase (Day 13–32), suggesting that thequality 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 extensiveculture in open ponds (17.5%). In Discus, larvae are dependent on thebody slime of their parent as a nutrient during the first two weeks ofexogenous feeding. Our observation demonstrated that Brown Discus larvaecould be raised in the absence of the parent fish by using rotifers asstarter food followed by Artemia nauplii. Their growth and survival ratewere comparable to those on parental feeding. The artificial feeding wouldeliminate the risk of larvae being eaten by the parent fish and shorten thebrooding interval of the spawners, thereby leading to higher yield of fry.This feeding protocol is less tedious and more practical for use incommercial farming of Discus than the existing strategies of smuggling thebatch of larvae to foster parents or feeding the larvae with egg food. Theuse of rotifers would enable freshwater larviculture to improve larvalperformance, increase yield, and facilitate breeding of new fish specieswith small larvae.