Techinically, a betta can survive in a cup of water, for a while. I am talking to you, walmart. I bought these fish to keep them happy and alive for as long as they can. Just now I found a green and blue doubletail girl that I had to take home with me. Though... the pet stores I go to are relatively clean, with varying degrees of quality. At some, I only purchase a fish if I really must have , then keep it in quarantine for a while. Though with most, I bring the fish home and see a translucent little thing, but in a few days they get colourful as they get a lot of sunlight where I keep them. In short, I do my best.