We have 1 Koi fish..but..it is going to get too big. Will try and explain it..we have a waterfall and where the water goes down is a pond. We have one Koi fish..but..it is going to get too big for the pond so when that happens, we are going to give it to some friends who want koi fish for their big pond. We also have gold fish and other kinds..not sure what the other kind are called and mosquito fish to get the mosquitos. All together we probably have 15.
We had a small pond about 20 years ago. It was about 4' x 8' and had a small "waterfall". The size was too small because critters would attack the fish and there was no where to hide.
So we live elsewhere now and have a pond about 12' x 16', it was safe from the critters and then a neighbors Labrador Retrievers found it, so we had to fence it in. We learnt a lot from our first setup and did well. The only thing we should have done with this one was we should have put in a bottom drain.
You're a nice person to adopt from the animal shelter. That's the only way to get a pet in my opinion. We have two adoptees right now.