Daphnia is great for bettas as a supplement. My explanation to oXson was specific to his request as he has stated he does not want to buy a bunch of different food and is saving for some other purpose(s).
B splendens are omnivores. However, since they are predominantly carnivorous omnivores, we feed them a diet that is 45% or above protein based. Bloat comes mainly from constipation as their digestive tracts are shorter than herbivores.
B Splendens: constipation
and the really long, technical analysis: Fish Nutrition
Personally, I would not use peas or beef heart. I will use Spirulina in a home remedy with a little garlic oil & shrimp or bloodworms. Fortunately, while FredFish is a little temperamental, his problems is boredom, not digestion.
However; when he root-pruned all my water lettuce, I had to consider why he was destroying my brand new plants. Was it because it's his bowl and he just did not like the roots hanging down or was he constipated due to the fact he had only come home 4-5 days before and was still acclimating? Both possibilities had to be taken into consideration because they are unknown variables. In any case, a solution had to be found. Fasting worked.