Advice needed
Hi, I'm a first-time medaka keeper looking for advice to help a specific fish. I got 5 juvenile medaka from my LFS a little over 2 weeks ago and put them in a planted 20 gallon. Unfortunately, after they've grown up a bit it looks like all but maybe one of them are male. The rest seem to get along well enough with their own little territories and brief chasing, but the one I'm not sure on spends its time hiding in the plants (so it's hard to get a good pic), and doesn't appear comfortable enough to venture outside of them for food. It doesn't look sick at all or like there's anything physically wrong- it does eat when food is in range, but it's just very timid. In the meantime, I've added more plant cover, but I wanted to ask for advice on if there's anything I can do to help it long-term.
For example, I have a planted 5 gallon I could move a few of them to, but I'm worried that'd stress them out or cause more bullying no matter which of them I move. I did ask the LFS about it and was told that it could be by itself in the 5 gallon, but can't find anything online about doing that. I'll look into returning it if that's the best option, but I don't know if the 30 minute drive and transfer would be even worse for it. I also thought about buying more to try to balance out the female/male ratio, but I'm worried that could still end up with too many males or more aggression. I really enjoy these fish, and I'd like to give them the best lives I can.
Sorry this is long, and thanks for reading this far!