How long can you keep a betta fish in the container?
Size Of The Fish
A maximum of 12 is recommended; for longer transfers, they should be in a proper storage container with an oxygen supply and a filter, if possible. On the other hand, small fish like Guppies, Neon Tetras, and Bettas can last up to 48 hours in a bag, provided that the bag is adequately aerated.
Can betta stay in cup overnight?
As long as air can get into the cup and the betta can’t jump out of it, yes, the betta should be fine. They are kept in small cups for much longer periods than “overnight” in pet and fish stores, after all.
Why are betta fish sold in cups?
Because they can and they must separate males. The bettas seen on display are males that fight and mutilate one another if kept together.