Betta Live Food
Mosquito larvae are the betta fish's natural food. Red mosquito larvae are called "bloodworms". Live brown worms and bloodworms are enjoyable to betta fish, but are notorious agents of disease and bacteria, as are most live foods.
If you decide to feed live worms to your betta, be sure to wash worms thoroughly. Never feed your betta fish worms from the garden or caught in the wild as they may have been subjected to pesticides.