I have two betta fish that I put into a homemade tank with a divider. I worked pretty hard at making the divider stable and prevent the fish from seeing each other. However, there seems to be a problem.
The fish are obsessed with putting their bodies sometimes in a vertical way, along the side of the divider. This is a picture I captured: http://i.imgur.com/gIXuA.jpg
but it doesn't express it perfectly. They would literally go on the side of the divider in a vertical way.
They would flare up, even though they couldn't see each other. It just seemed as if they knew the other was there. At least once, the blue guy jumped over the divider into the other side of the tank. I put plants around the sides of the dividers and did everything possible to limit the tiniest of cracks between the wall of the tank and the divider.
So now I am worried. They would spend several minutes, every hour, seemingly sensing the other and flaring up. They would either vertically line up on the divider, or be horizontal, but clearly seem aggressive -- as I suspect, sensing the other fish was just on the other side. Thus, I removed one from the tank to reduce tensions.
Is this normal? Is it even healthy? Or could the stress cause fin rot and other problems? I just don't know how to gauge this behavior. Any advice would be appreciated.
Because of some limitations, I am thinking about giving one of the bettas to a mature friend in hopes the betta has a better life, removed from the stress of constantly being under the threat of attack. But if it's not a big deal that they keep trying to sense the other one, then maybe I will keep them both in this set up.
Thanks in advance.