I thought I'd share my solution to keep my fish Nano as happy as possible and keep him heated while he hopefully gets better. I took a Sterilite about 1.5 gallons and stuck it in his 5 gallon tank. Most of edges are kept stable by the tank. the sponge filter is supporting the other end. I've heard of other people using cups and other things to support a container like this. I left the heater in the tank (it would have overheated the container) so no need for another heater. Nano has almost as much room to swim back and forth and he can see his tank. I could tell he was more relaxed as soon as soon he was back in there. He can still see familiar surroundings. He is little puzzled as to why he can't get his bridge. He is getting daily water changes.