Hello, A bit of background information about my male crowntail. Without getting into the entire story, he started his life (with me) in a small, unfiltered, heated bowl for a few months, moved into a 10 gallon for a few months, then into a 55 gallon for one month, and now he's back in the 10 gallon. The poor thing has been a real trooper, tolerating all my mistakes (such as putting him in a tiny bowl and dealing with high concentrations of ammonia, and making him share the 10 gallon with a BN pleco, a pictus catfish and a female betta). I felt badly about moving him back into the 10 gallon, but I don't want any altercations between him and the fish I plan to stock it with (currently three platys, soon to include more platys, tetras, and angel, maybe a gourami or two, and cory cats). He's not the most laid-back of bettas, and I didn't want anyone nipping at his fins, either. Anyway, a few days after moving him back to the 10 gallon, he started building a bubble nest. He's never really built them before (or at least I couldn't definitively say that bubbles in the tank were from him), but this one is pretty large (I base this on...nothing, really; it's about 3 inches square) and there are a few smaller ones in other corners. I've heard before that bettas only build bubble nests if they're healthy and happy. Is this true? I'm not asking about breeding; that is a whole can of worms I don't care to open at this time Do I need to do anything with it? IE will it mess with the water quality?