There is a fish up at my workplace that I would like to "adopt." I believe that it is a male Johanni (I hope to do more research to get it figured out). If I can get him out of his current (terrible) setup, would he be ok by himself in a 20L? I would like a bigger tank but I have the 20L just sitting around my house and I could cycle it with a filter off of one of my other two tanks (each has an extra filter on it for situations like this). Would this work? He is currently in a 10 gallon and I just can't stand it! Thanks for any input!