I have had my betta in a 2.5 gallon tank for about 7 months now and he is doing great. i do a water change about once a week if that. I have no filter no live plants or anything like that.
nursie said:The filters and heaters for the really small tanks like the 2.5 can be pricey, but I just bought one of each off ebay. You might try some of the online auctions to save some $$.
I work at a LFS. Not sure if you're aware, but the 'coloured' water you see isn't for show, it's a result of medication. Without the meds, the fish would succumb to fin rot, bacterial or fungal infections, ich, you name it. Living in an unfiltered small bowl cup isn't comfortable for them, I liken it to you living in a very small bathroom without a flushable toilet. Fine for the first day, unpleasant the next, and by the end of the week, downright disgusting.ShmooBeast said:If betta's can live in a cupfull of colored water at wallmart they can live in a few gallons of water just fine.