Hiram, Mats&a, Uwaguchi, yamaraki and Nihv Effects of Cultured Fish Feces on Algae Growth

In order to understand the role of fish feces in material cycling in aquacuhure grounds, the effects of cultured fish feces to algal growth rates were examined by feeding probiotic supplements under laboratory conditions. Four 1000-L round-shaped plastic tanks were employed for culturing red sea bream, Pagrus major (average BLF12.5 cm). ‘Ikenty fish were reared in each tank with a running water system. The fish in tanks A, B and C were fed on moist pellets with 1 % of Ulvapertusa fragments, 0.1 % of yogurts and 0.5 % of W. pertusa fragments and 0.05 % of yogurts, respectively. The fish in tank D were fed on dry pellets alone. The feces were collected once a day and fermented by a rotator for 14 days. Algal growth potential (AGP) was determined for the culture of Nannochloropsis oculata. The algae were inoculated by fecal medium which was extracted after fermentation in an incu-bator. The temperature and light conditions in the experiments were adjusted to 23oC, 7500 lux and 12L:12D. The feces extracts collected from tat&s A, B and C showed higher AGP in each trial. The feces collected from tank D presented always lower AGP The highest popu-lation density of N. oculara, 34.8 x lo6 ceUs/ml, was observed in tank A which was fed moist pellets with 1 % of 0: pertusa fragments