So I have a small cold water tank with a platy and a river loach in it, Iv had them for a couple of months it has a filter but no plants or anything, I noticed about 20 fry swimming around about an hour ago so I put the platy in a temporary separate tank until I can buy a new one, what now? Does the loach need to be moved too? Could the filter suck the fry in?
I don't know what a river loach is, but for almost all fish, if it can fit something in its mouth it will eat it. The fry need to be raised in a separate tank, but unless you can provide a much larger tank to keep them in when they start to grow, or you know already where you can rehome them, keeping them won't be very practical so you may want to let nature take its course