I'm pretty sure I never put a plecostomus in there. Where you come from plecostomus. Have you ever torn a tank down and found a scaly beast staring at you all GOAWAY. PUT THE WATER BACK. >O
Don't have a pond, but I found a 6" sunfish in one of the birdbaths at my parent's house. The nearest body of water is about 2 miles away.
Funny things happen.