It would be just to put an extra 20 - 80 dollars a month or two months in my pocket.
I really don't mean to be negative because I can see you are really excited about this concept. And although what you have in this thread is an interesting concept (with plenty more to research), with the initial upfront cost and the ongoing monthly utility/maintenance costs, I don't see how you would ever achieve a profit. But, maybe I'm wrong. All I'm saying is don't do it if that is your expectation (even in the long term). You are already talking about getting into a larger home at somepoint, so you have a short term timeline to make your profit, not long term. And doing all of this will not add to the resale value (could even devalue) of your existing property.

Then, there are the fountains that freeze here, inground pools get 90 degrees, utilities...

As far as research, I'd search for some island that gets hot/cold like here (if you can find one), then see how they aquaculture stuff there.

Have you considered having all of it inground? (Viewable only from the top?)