I think somebody else brought this up but could you get a kiddy pool that little kids play with in the back yard, fill it with water, get a fully submergable heater and put it at the bottom of the tank and run a filter in the tank and put fish in it and put it in your basement?
When fish are in a tub they are hard to observe from above. They tend to try to hide when approached from above but safe definately. lights?
I put tubs outside every summer and its really cool, the plants just go wild and the fish are much brighter colored. just some thoughts