Until I posted on here about feeding my bettas peas, I had never seen anything that even hinted that peas could be bad for bettas. It worked for my constipated female who pooped only about five minutes after I fed her half of a pea. (She hadn't gone in over a week!) I have yet to see a reason for it being bad. I know that bettas are carnivores, but so are cats and it's good for them to eat grass. :P What exactly do peas do that's bad? Is it just one of those things that is up for debate, like aquarium salt?
Note: The pea was canned, so it was soft. I can see why a frozen pea/uncooked pea could be bad.
Edit: Is it only bad when the fish isn't constipated?