Does everyone know this but me?

Sometimes you find out something that everyone else is all, oh yeah, of course, and you have to wonder, how did I miss this common knowledge? 

For example, the peas that we gave La Principessa for her constipation. I was telling my sister about this and she said that she gives them to her fish when they get constipated (????), as it clears them out too.  FYI, did you know that when fish get constipated, they have trouble swimming and tend to float up?  I didn't, but again, maybe that's common knowledge and I'm just clueless.  And weird to think that what works for babies also works for fish, but as the Texan said, we do share a lot of our DNA with them.