I looked into this a good bit actually, and something you need to be aware of is that some of the liners used in those pools are made to deal with a pool pH of 7.0-7.6, which isn't a big deal if you're keeping fish at that pH. Lower pH can shorten the life of the liner. Also, some of the liners are impregnated with chemicals to kill bacteria and aid in pool water chemistry, which are usually the opposite of what we fishkeepers are trying to achieve. I read that you could use heavy baths of potassium permanganate for a year without fish to eliminate the chemicals.
Point is, call the manufacturer, and find out what's in the liner before you buy it! I don't know about specifically asking if you can keep fish in their liner. They'd likely say no.
Point is, call the manufacturer, and find out what's in the liner before you buy it! I don't know about specifically asking if you can keep fish in their liner. They'd likely say no.