Originally Posted by Bambi
They shouldn't be in constant view of each other anyway. Your should either separate the tanks, or keep the paper there.
People who have tanks side by side will often "exercise" and stretch their fish by removing the paper for a little while each day to get the fish to flare and swim around. When trying to get a super delta to go into a halfmoon, this often helps(just as a side note ><).
There is no harm in having them side by side, as they normally do get used to each other and would flare at one another about the same amount as if one exercised them. Sometimes less as one of my boys doesn't flare at his neighbor at all. As long as there are some tall plants to break up the view, it is fine.
I can agree with the statement "They shouldn't be in constant view of each other
" if they were in bare tanks with no covering. But well planted tanks, there is no reason they can't have view of their neighbors. I'd say a good chunk, if not more then most owners of multiple bettas have their bettas in constant view of one another. Think of how many divided tanks there are out there.. breeders with their jars and small tanks next to each other one by one.
Some bettas don't do good with neighbors, but most will calm down and be fine with them in time. Also another point is that many people will tell you when they kept their bettas apart, they become "depressed". Bettas are actually pretty social and seeing each other can make them more lively and happier. I think there was a thread about it somewhere here where people were talking about how social they actually are and how good it was for them to see each other. So I wouldn't say it's bad to keep them being able to see another.