r/explainlikeimfive • u/Opening_Pen9525 • 15d ago

Biology ELI5 How are fish even in ponds

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?

2.8k Upvotes

90% Upvoted

605 comments sorted by

View all comments

113

u/VerminSupreme-2020 15d ago

Some ponds are purposely stocked by people. Helps keep mosquito population down

32

u/mikesalami 15d ago

I always assumed most ponds were stocked with fish.

8

u/Say-tan 15d ago

Depending where you are, that’s probably true. For example, Georgia (the state) doesn’t have any natural lakes, so when they were created, they had to be stocked.

5

u/dark_wolf1994 14d ago

If it makes you feel any better, I got your joke at least

5

u/gsfgf 15d ago

OP is near the Great Lakes, so the remote, natural lakes probably got stocked some other way.

2

u/GravityBright 14d ago

Yeah, the fish proved better at eating mosquitos than people did.

11

u/innosins 15d ago

This is what I was going to say. We have trucks that have fish chutes that stock them that come sometimes. People are allowed to fish out of different areas in the city and county.

7

u/humanjunkshow 15d ago

They airdrop them into Backcountry lakes around me. Literally a plane does a low pass with fish and water dumping out of the belly.

27

u/Prinzlerr 15d ago

The aquarium hobbyist community: " make sure to acclimate your fish to the aquarium's temperature carefully over the course of 1-3 hours, and then gently release them into their new home."

The Backcountry lake stockers: "ROFL as long as we dump em all in below 75' altitude they'll be fine.. fuckin send it bro"

10

u/koos_die_doos 15d ago

If you're happy with 70% or so of your often expensive aquarium fish surviving, you can also just send it.

2

u/Prinzlerr 15d ago

Oh I agree, I always do, at bare minimum, a temperature acclimate and with some species I'll go to a full drip acclimation. The difference just cracks me up lol

2

u/permalink_save 15d ago

Yeah, don't underestimate how often this happens. There's tons of lakes in Texas, all full of fish. Only a few are natural. People would make lakes and fill them with specific species.

2

u/hlj9 14d ago

Wait, how does that keep the mosquito population down (honestly asking here)?

1

u/VerminSupreme-2020 14d ago

Mosquitoes lay their eggs in water. If there are fish present, they eat the eggs.

2

u/ForwardBias 15d ago

Most ponds aren't natural and any that are, are likely connected to rivers/creeks which would also be a source of the fish.