Analysing the diel feeding patterns and daily ration of Nile Tilapia, Oreochromis niloticus (L.), in Laguna de Bay, Philippines

Cage cultured Nile tilapia, Oveochromis niloticus, were sampled at a commer cial set-up on two occasions in 1995 in Laguna de Bay, Philippines, each ti me over a 24 h cycle. The stomach content weights were averaged for each su bsample and analysed with the computer model MAXIMS. The model predicted th at, in May, larger fish (mean total weight: 31.5 g) feeding on natural food alone fed continuously from dawn to dusk, ingesting 5.1 % body mass equiva lent (% BME, wet weight basis) whereas smaller fish (mean total weight: 9.8 g) had two feeding periods per day, from sunrise to mid-morning and again from mid-afternoon until after sunset, ingesting 13.7 % BME. In August, fis h were given supplemental feed once daily at 07:00 h. These fish (mean tota l weight: 81.7 g) fed intensely until supplemental feed ran out before mid- day, after which some ingestion of natural food took place later in the day . The fish ingested 5.8 % BME supplemental feed and 5.1% BME natural food p er 24 h. In May, most of the stomach contents consisted of the blue-green a lga Anabaena spiroides, whereas in August, the natural food was made up pri ncipally of detritus.