I put my three bettas in a 3 way divided 10 gallon tank today. My new betta and one of my older ones is doing fine but my one is wrong. I made a buffer for my filter so the water splits in two and he's been hanging out between the two waterways and now for some reason his mouth is stuck open. He's blowing bubbles and going to the top to breathe but his mouth is stuck open. I don't know whats wrong with him. Please help.
He's breathing really fast and his fins are moving really fast too.