I have two bettas. One I have had for about 6 months, the other about three weeks. Vito is new (CT), and Cash is older (VT).
I just moved Cash into a divided 10 gallon with Vito, and already my littler betta is showing a stress stripe. Cash is flaring all the time. I can't move anybody back to their old tanks (plastic was cracked in transport =( ), so they must stay together. But I am worried for Vito's health. Will he be okay??? I put stress coat in there for them! Cash is being extremely aggressive, but I'm sure they can't get to each other.