I second that you should get the biggest tank that your space or finances allow. And don’t rush into it. If you rush things like I did, eventually there’s a payback time where you may have to put in more time and effort to rectify issues.
Take your time to plan the equipment and livestock list too. If there’s a budget, you can take time to look for good used deals at the pasar Malam section too.
Enjoy the journey and welcome to the dark side.