I would have a room for community fish - BUT nothing that would outgrow the average 100l or so tank - no Gibbiceps/Common Plecs, no RTBS, no Oscars etc.
In a seperate and much larger room I'd have oddballs and plecs, specialising in smaller species to make them more appropriate for more fishkeepers.
I would sell mature filter media too. (or give a bit free with every fish - just in case!)