Why some people keep trying to find excuses when they know full well what's right and what's wrong is beyond me.
If you really want to do it, do it, just don't pretend you care about the fish or it's the right thing to do.
This is a BS answer.
I think it is not a bad thing to do, personally. (At the moment at least.) But, im still looking into others opinions to see how i will decide.
Nothing in this worls is right or wrong. Everything is changed by perspcetive.
For example, let me take the ethical standpoint. On one hand, im saving a fish from a 20 gallon tank in a store crammed with 15 other fish. And it could easily end up in the same situation if someone buys it. But on the other standpoint im putting it into a situatuion where it is, admittedly, pretty tightly squished in.
Or even a logical standpoint. A small tank doesnt technically limit a fish unless the fish is big enough that its unable to move. The food and water quality is what is important. In smaller tanks with bigger fish, it becomes difficult to maintain but not impossible. So it should work, right? But you could still come up with research saying that fish are stunted in enviroments that are too small, and have shorter lifespans.
Everyone counteracts each other. Neither is right or wrong technically. Im trying to decide what i think is right, and even if i do decide its fine, this is still a hypothetical situation that may not even occur.