Preliminary trials with an ultraviolet liquid sterilizer

The effects of a new ultraviolet liquid sterilizer were tested in fresh- and seawater aquaculture installations. Ultraviolet treatment reduced the population of aquatic microorganisms. The mortality rate of experimentally wounded fish kept in sea water treated with ultraviolet radiation was significantly lower than that of controls. A further comparison was made between ultraviolet and chemical treatment of wounded fish. Ultraviolet radiation reduced bacterial population in a marine fish hatchery, but the larval mortality did not decline, probably because of other environmental factors. The use of ultraviolet sterilizers in fish culture is discussed.