I have about 20 tanks set up, 5 are unheated, 5 are unlit.
In winter, the fish portion my energy bill hovers around $225per month, in summer it drops to around $100+(lights and pumps, most heaters unplugged) .
Add another $30 per month for water.
Add a 2000 gal pond in summer, so one extra pump.
I have all the fish in an out building, and on separate meters.