My flag fish has an overwhelming preference for stringy shaped foods. I tried zuchini and peas and algae wafers, he has almost no interest in those. He gets most of his veggies from eating roots, mostly of floating plants and also from some of the rooted plants. He will also bite of the tips of tenellus. It has to be long and thin and string shaped or he doesn't want it. He'll eat duckweed leaves, but mostly he likes the roots. I'm starting to think that the reason my red root floater is dyeing out is because the flag fish is eating the roots.