Welcome! Can't help as far as the tilapia are concerned, I'm too far north. All I can contribute is the advice to be patient. It takes time for all the pieces to fall into place. I think you will get a great deal of satisfaction out of your project, if you see it through.
For heating you can look here
For tilapia you can try here
They are all in the forum section at the top of the main page, or you can use the search bar there as well.
You can also join groups(tab at the top of the main page) that can help you with your particular type of AP goals.