So question one... what is the footprint of the pond? Also, what hardware do you have on it right now? Full list of hardware.
The biggest struggle with keeping large fish like that is providing the necessary space. Volume usually isnt the worry, it's the footprint. The second concern would be filtration. I know the ray tank they had at the Aquarium in Kemah usually had a nitrate level of around 250ppm, and while the fish did ok, it surely want the best scenario for them. So a sump/filtration area would be well adviced.
The biggest struggle with keeping large fish like that is providing the necessary space. Volume usually isnt the worry, it's the footprint. The second concern would be filtration. I know the ray tank they had at the Aquarium in Kemah usually had a nitrate level of around 250ppm, and while the fish did ok, it surely want the best scenario for them. So a sump/filtration area would be well adviced.