SURFACE DISINFECTION OF RED DRUM (SCIAENOPS-OCELLATUS LINNAEUS) EGGS LEADING TO BACTERIA-FREE LARVAE

Intensive egg incubation techniques provide favorable conditions for m icrobial proliferation, which often leads to massive mortalities of fi sh larvae. Vertical transmission of microbes from parents to offspring s can be eliminated by disinfecting the eggs before hatching. The effe cts of exposure of red drum (Sciaenops ocellatus Linnaeus) eggs to dif ferent disinfectants on 24-h larval survival were evaluated following a toxicological approach, involving the determination of the ''No Obse rvable Effect Concentration'' (NOEC) for each germicide. The NOECs of the different disinfectants were evaluated at different stages of egg development. The early tail-free stage of development was the most res istant to all germicides. Successful disinfection of eggs was achieved after a 5-min exposure to hydrogen peroxide at 3% concentration, lead ing to bacteria-free larvae. No adverse long-term effects on either la rval survival or growth resulted from the egg disinfection treatment. Other marine fish species tested, yellowtail snapper (Ocyurus chrysuru s Bloch) and spotted seatrout (Cynoscion nebulosus Cuvier), were more sensitive to hydrogen peroxide than red drum, so the toxicological app roach used to select the disinfection treatment for red drum should be undertaken for each target species.