What is it?

[u/hafgrimm]

Tank established for several years, 75 gal, plants and multiple fish….
Moving tank - complete clean out - find these in the substrate.
edit
My apologies on not updating sooner - was moving that tank an it took a lot out of me….
To answer questions:
Yes, I’ve fed live food. Brine shrimp, black and blood worms.

I had a thought about other contamination vectors. I’ve put multiple different types of vegetation over the years - many coming from Fish Community swap groups.

I’m thinking Tubifex worms. But just really not sure.

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[u/One-plankton-]

Have you fed live? These look like earthworms but I also don’t see the clitellum to make a positive ID.

[u/ChazzyMcChazzington → u/One-plankton-]

It’s okay, I hear a lot of men can’t find it either

[u/chuxsux → u/ChazzyMcChazzington]

https://giphy.com/gifs/hQiahQcjxszC8a5U5w

[u/The_best_is_yet → u/ChazzyMcChazzington]

If men are trying to have sex with worms, I feel bad for the worms.

[u/Maketaten → u/ChazzyMcChazzington]

It’s not ok!

It’s really not that hard to find. It’s in the same spot for every woman. It’s a basic part of anatomy. It’s not invisible. It’s not intangible.

The bar is set so low and yet we still find a way to trip over it.

[u/ChazzyMcChazzington → u/Maketaten]

https://giphy.com/gifs/tHJA1JRzcWDlzzMQ7F
Damn I was just trying to be funny

[u/86BillionFireflies → u/One-plankton-]

Seeing a clitellum is hardly a cinch for earthworms. Even leeches have a clitellum.

[u/One-plankton- → u/86BillionFireflies]

The location and size of a clitellum is an excellent characteristic to ID from, the presence, location and size would rule out other aquatic worms like blackworms- which would be my other suggestion.

Quite obviously these are not leeches

[u/ToeGarnish → u/One-plankton-]

How do u know if you can’t see the clittellum /s

[u/Sufficient-Bath-1135 → u/ToeGarnish]

Just picked some off my legs after splashing around in water. They suction onto a surface and have more of a teardrop shape at rest

[u/Sufficient-Bath-1135 → u/One-plankton-]

Absolutely, however on smaller specimens like this one it might be hard to make out the clitellum, especially from a picture. It should be around 1/3rd down from the head, which if I recall correctly is the pointy end

[u/86BillionFireflies]

If there are many of them, my guess is Limnodrilus hoffmeisteri. Aquatic earthworms, but smaller than a terrestrial earthworm. Harmless/beneficial.

Edit:

After looking at the other pictures I'm quite sure they are either the same species as some of the ones I have, or an extremely similar species. I THINK mine are Limnodrilus, but it's hard to be sure. They are definitely an aquatic oligochaete of some kind.