FishBase has tons of data on tilapia food items and other material. One thing can be said about all them - they will eat whatever type of plant material (plankton , algae, macrophytes, detritus ,vascular plants , insect larvae, small crustaceans , FA , etc ) that is available if the others are in short supply. Preferred food item studies/data have to be reviewed carefully to account for all the potential factors that might influence the conclusions such as time of year , temps , variety and volume of sources , fertility and size of forager.