"Diet: In the wild, they feed off of mosquito larvae, mosquitos, other insects and their larvae, daphnia, and worms. In the home aquaria many bettas won’t eat flake food. If you choose to try offering flakes, please be sure they are specifically betta flakes and not tropical flakes. Tropical flake food does not provide the proper nutrition for a betta. Meaty foods should be their staple diet. Vegetables should be avoided. Peas are sometimes suggested for bettas, please don’t. A betta’s digestive tract is not designed to handle that kind of roughage in their diet, thus the reason it acts like a laxative. Feeding peas to a betta can severely damage their digestive tract and lead to permanent damage and early death.
-Tank Region: All over, but mainly the Top."http://www.bettafish.com/showthread.php?t=20058&highlight=feeding+peas
I don't think you're supposed to feed bettas peas....