Wokka I reckon the fish cost more, every tank has a filter, heater and pump running all the time plus a light on sometimes, the turtle tanks have a uv light and a spot lamp 12 hours a day and external filters. Some of the large tanks have a small internal filter as well mostly for current. One of the large tanks has a metal halide light which looks great but costs heaps. In summer I have to have the ac on in the room so they dont cook but in winter it stays pretty stable at about 22-24 from the amount of water. Good room for reptiles because of that. It also has the poker table in that room and sometimes that costs me a bit Chris1-That sounds nice, I have never been paid for electricity before, fingers crossed when the solar is up I will.