^^
You're talking about an almost 7 foot fish that is known to be pelagic, and therefore most likely active, in what is essentially a midget tank for a fish like that. The closest approximation I would know of, would be to compare them to captive care of other large billfish like sailfish and marlin, or highly active pelagic sharks like blues and threshers.
I know I commented on your thread on river sharks, but take a good hard read at the Elasmobranch Husbandry Manual, as well as its 2007 follow up counterpart. It took me 3-4 days to get through it, and that's reading at maximum speed and comprehension (for context, it takes me about 30-60 minutes to get through the first harry potter book). The ARV (active ram ventilator) sharks are going to be your closest approximation, and even then I might even double the recommendations.
A better option for a 1000 gallon pond might be something like fusiliers. You're going to be hard pressed to find a billfish lookalike. Fusiliers would also provide a pelagic fish that's highly active, colorful, and predatory.
