I've got some reptiles in addition to my reef and a pool. We hit $700-750 for 2 months in a row. Our normal is around 4-450. Usually about the same winter/summer for us.
Peak hours kill for sure, so does getting into different usage tiers. It just starts to really add up. Turning off my heat (electric) during the day helped a ton. I also adjusted my tank's photo period earlier in the day to avoid peak hours. I got lucky with the heat off and running metal halides that is basically offsetting my 300w heater. My fan rarely kicks on, same goes for my heater during the day.
Moving my light schedule earlier, moving my pool equipment to run earlier and just paying attention to all the small things like lights ect in the house my last bill was back down to $450.
I'm thinking about going solar, but first I plan to insulate my walls. Ain't a shred of insulation in any of our exterior walls here!