Thanks Mike. Ask this question and you will get a myriad of answers. I've kept this particular species....a hands down favorite of mine...for close to forty years. I've kept them in as small as a 75 gallon tank and as large as the 1600 gallon pond. The one consensus is that bigger is always better. Without trying to go all "yoda"...it's not the water they use as much as it is the water they don't. Bigger bodies of water will generally be much easier to keep in better shape. In the wild, they may only occupy a relatively small space. But in actuality it's not the area but the total volume of water they are in. Most often nature will give a helping hand with water changes...and I think rarely will that space be limited to a 75 gallon volume. t comes down to survive or thrive. I put fish from the same parents in both the pond and a large tank. Without fail, the fish in the pond would grow 30-50% faster and larger. Good luck with the managuense. Awesome fish.
Mo