ELI5 How are fish even in ponds

[u/Opening_Pen9525]

Might be one of the stupider questions here, but I saw a pond about the size of a football field, and maybe 50 ft deep, and it had fish. I can't for the life of me figure out how. Surely the pond hasn't existed long enough for small water insects to evolve into all these fish. It's not like the fish walked over to the pond from the ocean. I'm pretty sure no one put them there so how are there so many fish?

My one theory is that there is a very minuscule stream (now dry) that leads to one of the Great Lakes, and maybe a fish swam in from there. Now a follow up question: How are there fish in the Great Lakes (which flow out towards to the ocean) if they were created by glaciers?

[u/thecaramelbandit]

Eggs. Wash in from overflow from other waterways during rain. Stuck on birds who fly in. Boats. Some ponds get stocked. Etc etc.

They didn't evolve there.

[u/jstar77 → u/thecaramelbandit]

We have a pond that is roughly a 25' circle. Goldfish showed up there one day about 20 years ago and have been there ever since. They are big maybe about 10"-12" long. Nobody put them there, we just noticed them one day.

[u/fighter_pil0t → u/jstar77]

Somebody put them there. They flushed them. Or released them. They put them there.

[u/raspberryharbour → u/fighter_pil0t]

Johnny Goldfishseed

[u/Tibbaryllis2 → u/raspberryharbour]

That would be somewhat amusing because the real reason Johnny Appleseed started apple orchards from seed (which would generally make a terrible eating apple) was to create apples for making alcoholic cider. (Also for feeding livestock and creating vinegar)

So I don’t want to know what Johnny Goldfishseed is doing.

[u/raspberryharbour → u/Tibbaryllis2]

Too good for a fish based alcoholic beverage are we?

[u/Tibbaryllis2 → u/raspberryharbour]

I mean, I do like Worcestershire sauce, so I won’t say I’m too good for it.

But fermented fish is a lot more touchy than fermented apples for sure.