RECIRCULATING-WATER SYSTEM FOR THE CULTURE OF MARINE TROPICAL FISH LARVAE

A recirculating-water system was designed for raising larval fish that concentrated larvae and prey while keeping them suspended in the wate r column and maintained good water quality during a 3-4-week rearing p eriod. Incoming ambient seawater was tested and found free of chemical s potentially toxic to larvae, except for petroleum hydrocarbons. An e xternal filter, consisting of activated carbon, crushed oyster shell, and biofiltration material, reduced the petroleum hydrocarbons and mai ntained low levels of nitrogenous compounds throughout the larval rear ing phase. Larvae of red drum (Sciaenops ocellatus), used to test the system, had a 55% survival rate, which was as high as has been achieve d previously. Three species of tropica were reared in the system. High survival of cubbyu (Equetus umbrosus) to metamorphosis (18%) and limi ted, but promising, success with spotfin hogfish (Bodianus pulchellus) and yellowtail snapper (Ocyurus chrysurus) demonstrate that the desig n can be applied to the culture of ornamental fish.