I would say yes that they can live without a filter depending on what size of tank you are going to be putting them in. You will however need to have some sort of surface agitation so that the water will stay oxygenated. If the tank is not cycled then you will have to perform small waterchanges to keep the ammonia leves down so that the fish do not die. The disadvantage of this is that the beneficial bacteria will take longer to form, and the colony will not be as large as what it would be if you were not doing the water changes. Cycling with small water changes also takes alot longer.
Currently I only have one tank, other than my saltwater tank that has a filter on it. I take that back, they all have filters on them, but I dont use any filter media, I just use them to cirrculate water and for surface agitation. The only time that I throw in filter media, activated carbon, is when I need to remove meds from the water. I have only had to use meds one time, so other than that week that I had the carbon in that one tank mine have been running with basically no filter at all.