A cure for a bored male Beta

I have a male beta in a 20 gallon with some amber and cardinal tetras. He doesn't do to much moving around except when he's fed.

Last night I moved my adult guppies into the 20 gallon because I felt like they've produced to many offspring already for my little 4 gallon cube. Male Beta is now the most active fish in that tank! He's been flaring a lot at the guppies, but so far hasn't done anything about it otherwise. I'm keeping a close eye, I suspect he's a little confused and thinks they might be younger beta's. At any rate, it's been some fun entertainment to watch. I've read that typically if the beta isn't nipping at them that the flaring will calm down after a couple days.

Another behavior I noticed about my beta a few weeks ago is that he does occasionally chase an octo if they get to close to him.

I had put a couple of guppies in with a betta I had and was surprised that he ate them. I thought they were too big but apparently he didnt think so.

Yikes! well these guppies are full grown, so about half the size of the Beta. He's becoming more aggressive now and has been chasing them, I'm a little worried that they're not going to work out together after all.

My betta loved the cories I had in the tank with him. They used to play a lot and it was fun to watch. And the good thing was they were too big for him to eat and big enough on their own not to be intimidated.