I got a tank a lot like this as a gift for my girlfriend a little over a year ago (it wasn't a Little Mermaid tank, but it was the same set-up). She has had the same betta living in it ever since. The betta seems very happy. I've never noticed an ammonia burn and he has nice, long fins. He also starts to wiggle around (a happy wiggle, not a stressed wiggle) when you walk up to the tank to look at him. She isn't an experienced fish keeper and I know that she isn't as diligent on her water changes as she should be, but the betta is doing great regardless. Your daughter should be very happy with her X-mas gift.