What type of "outdoor fish" are these?

[Nells250]

Can anyone ID these "outdoor fish"? I see them in a lake/pond in central-eastern Massachusetts. They are maybe a few inches max, and seem to hang out at the shore line when the sun is out.

 

[GaryE]

They look to me like Fundulus diaphanous, the barred killifish. Check them against pictures for the species online.

 

[Back in the fold]

This is a book everybody should have . If I’m going out to where there’s water this goes with me .

 

[Back in the fold]

Here’s the information from the book on the fish Gary guessed .

 

[Nells250]

A FB group also thinks Killifish. Some of what is on that book page does make sense, like the sand in their habitat. The shore of that lake is sandy.

 

[GaryE]

Where you are, you should have at least two distinct species of Fundulus killifish (heteroclitus as well as diaphanous), with the possibility of a third if you are south enough. F. diaphanous, the banded killie is pure freshwater (the other likes some salt). I have never seen them anywhere but over sand, where they feed by picking though the substrate. They are our local version of Corydoras, as far as their niche/lifestyle goes.

It was legal for me to catch and keep then, so I brought some home and they bred in a pond. I now live 800 km east of where I kept them, and there are slightly different forms here. What were pale green fish inland are a prettier bronze fish here along the coast.

I met some University of New Brunswick scientists who were studying the brackish species, F heteroclitus, as locally they are found breeding and thriving in water nothing should live in. They have lived for generations in a stream that meanders through an oil refinery. In places along the US coast, they also live in hyper polluted water and the researchers want to know how they can adapt. So these little fish come from a good family with increasingly well known cousins (the local name along the coast for heteroclitus is mummichog).

They'd be good aquarium fish if their life cycle didn't need winter conditions.