Well, I have had the worst of success with fish. I made my pond 30 gal and dumped 4 fish in it. 2 reg blackies and two fantails. Those all did well and thrived. All I have left now is the two blackies. The two fantails, I fear were lost to predators, snakes or jays. I also bought 10 cheapy goldfish expecting a few wont make it. I was right. 90% failure rate at this point. Only one is thriving. So, in the end...for my new pond, all thats left is 2 blackies I never see and one goldfish from the new batch. Kinda discouraging tbh. i hope as the pond matures and balances out, the success rate will be higher.