46 MARCH 2013 • WORLD AQUACULTURE • WWW.WAS.ORG (Fig. 4) using commercially available fertilizers ammonium sulphate, super phosphate and urea at 10:2:2 ratios for 1000-L. An outdoor mass culture of rotifer Brachionus plicatilis was prepared in 1000-L translucent tanks (Fig. 5) by feeding with microalgae. Artemia cysts were hatched in separate 200-L black circular fiberglass tank with vigorous aeration and illuminated by a 100-W bulb for 24 h. Clownfish Clownfish larvae were stocked into 100-L, square, grey FRP tanks at 3/L (Fig. 6). Rotifers enriched with algae were added to larval-rearing tanks at 6-8 rotifers/mL as the initial feed, three times daily (1000, 1300 and 1600 h) for the first ten days. Rotifers were substituted with newly hatched Artemia nauplii at 3-5/mL from the eleventh day. Boiled and finely chopped clam meat was fed to juveniles from 25 days after hatching onward. Gentle aeration was provided to maintain an optimum level of dissolved oxygen and to achieve homogeneous distribution of the added live feed. The tank bottom was cleaned and 10 percent of water was replaced daily without disturbing the fry. Water quality parameters were monitored daily and light intensity was 600 lux. Larvae developed parental coloration and metamorphosed within 15-18 days after hatching. For the first two weeks, larvae were pelagic but gradually moved to the bottom during this period. After 20-25 days of rearing, fish were transferred to rearing tanks, where sea anemones and a canister filter was provided and fish were fed with minced boiled mussel meat. Juvenile clownfish attained market size within three months of hatching (Fig. 7). Damselfish Newly-hatched larvae of damselfish were 2.0-2.5 mm long and three days after hatching had a mouth gape of 35-40 µm. Cultured microalgae and plankton collected from estuarine water (10-20/mL) were gently added to 100-L, circular larvalrearing tanks. Up to 20 days after hatching, larvae were fed with algae-enriched wild plankton (copepod nauplii, chaetognaths (Sagitta), mysid shrimp, ostracods and zoea) and later, freshly hatched Artemia nauplii were supplemented (3-5/mL). Larvae attained parental coloration around 25-30 days after hatching and 2021 mm in length. Damselfish grew to marketable size in about five months (Fig. 8). Challenges of Larval Rearing Successful larval rearing of marine ornamental fishes depends on the appropriate size and nutritional quality of live feeds. Among marine ornamentals, success was achieved in the breeding and seed production of clownfishes, inasmuch as larviculture protocols are comparatively easy because the mouth size is moderately large. We demonstrated that broodstock development, breeding and larval rearing of clownfish and damselfish is possible using brackish (23 ppt) water. In addition to water quality, nutritive feeding and appropriate photoperiod also influence successful hatchery production of these species. Approximately 10-20 percent of larval (clownfish) mortality was observed during the first two days after hatching. This may have been caused by stress and injury caused by transfer from the spawning tank to the larval rearing tank and also in accepting the first feed. Mortalities were also observed during weaning fish larvae from rotifers to Artemia. In the case of damselfish larvae, mortality was approximately 50 percent during the first few days, largely due to problems experienced in initial feeding. UnFIGURE 5. Mass culture of rotifers. FIGURE 3. Submerged biofiltration unit. FIGURE 4. Mass culture of Nannochloropsis microalgae.
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