NUTRITIONAL-REQUIREMENTS OF REDLIP MULLET .3. PRELIMINARY EXPERIMENT ON THE REQUIREMENT OF LARVAL REDLIP MULLET FOR ESSENTIAL FATTY-ACIDS, AND THE SUPPLEMENTAL EFFECT OF NANNOCHLOROPSIS TO REARING WATER

A feeding experiment for redlip mullet larvae (4.58+/-0.25 mm TL) on t he EFA requirement was conducted by using rotifers enriched with ethyl esters of four kinds of fatty acids: linoleic acid, LA; linolenic aci d, LNA; eicosapentaenoic acid, EPA; docosahexaenoic acid, DHA. Larvae receiving rotifers enriched with LA and LNA showed typical symptoms of EFA deficiency syndromes, and obtained poor growth and high mortality . On the other hand, the larvae receiving rotifers enriched with EPA a nd/or DHA showed better growth, activity, and survival rates. These re sults suggested that the redlip mullet larvae required n-3HUFA like EP A and DHA as their essential fatty acids. Also, the supplemental effec t of unicellular alga Nannochloropsis sp. to rearing water was investi gated from the view point of EFA requirement. The n-3HUFA content in r otifer cultured with Nannochloropsis decreased linearly after they tra nsferred into sea water. However, when 40-50 x 10(4) cells/ml of Nanno chloropsis was introduced to a rearing tank, the n-3HUFA content in ro tifer remained without decreasing for 6 hours. The larvae reared in th e tank with Nannochloropsis supplement showed better growth than those of non- or fewer-supplement groups.