... I'm gathering the knowledge so I can build ponds for those enthusiasts who have kept these fish for the decades that is required. All I want to do is provide an opportunity for those people to do so.
If I get it right, that seems like a cool, novel idea of a service that's not yet provided out there. There may be a niche market for it. Of course, those who have a lot of money can already find that service and e.g., have their monster tank built out of acrylic like on those TV shows. I imagine your edge would be an offer of an economical construction for the those in the middle class - neither millionaires, nor DIY-ers. Of course, a viewing window is a must, a large one, and perhaps multiple ones. I don't think you will find much interest from people for simply ponds.
...How tall should the walls be? I see that OFR doesn't have any.
OFR don't keep fish that can or are known to jump out of the pool pond, I assume. An Arapaima can clear a few feet, so I'd think 5' walls around the enclosure could suffice. This is where a netting would be more economical but maybe less convenient in use.
...Also for figuring out filtration. I need to know the protein contents of frozen bait food so I can calculate how much filtration I need. Would you know the protein contents of the common food for them?
The pellets usually carry 40% protein. The frozen fish can be thought of to consist of 70%-80% water, the rest roughly all protein. Just my thoughts.
On your database that lists the temperatures for the fish. When it has the climate but not the water temperature for the fish, so I just go by what water temperatures occur in those climates? If so, what is tropical, subtropical, Temperate water temperatures?
Very roughly... tropical is steadier, 70-90 F; subtropical can vary wildly, down to 45-50 F during cold spells and up to 85-90 F; temperate usually freeze over in winters, so 36 F for the low, don't exceed 65-75 F in summers. Just my thoughts.