My betta Ninja imediately built a huge nest right when I put him into my divided 10gal, while the other 3 bettas barely worked on theirs. From experience, Im going to say it depends on the fish regardless of same conditions.
Sky is the new addition to the tank. His caudal fin was like that ever since I got him like I said. The pet store where I got him had a lot of bettas with messed up fins, chances are they're from rotting.
Hmm, is there anything I can do for his caudal fin?
My set up of 2 dividers went pretty well, so I decided to make another unit since theres plenty of space. Everything fits perfectly, the dividers I used were for 15/20gal, but a pair of scissor fixed it without problem. And I also lowered the current by placing a sponge from my previous sponge...
Well I thought they would get along. And Im not joking when I said Ares killed my oscar. Fins were nipped and scales pealing off, next thing you know the oscar died! ._.
edit: love that tank millym~
I wouldnt worry about a fish getting bored. Is not like you can buy them a PS3 and Rock Band. Bubble nest is a good sign, keep what you're doing. Regarding companions, I dont suggest it. My Betta killed my oscar, and even attacked some corys that I put in this tank. Maybe they're bad tank mates...