What are these?

Question

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I have been seeing these around my tank, above the waterline! They move and duplicate if cut in half. They do NOT have a triangle head. If they get in the water they are light pink and they squirm around.

There are not many around the tank. Just a couple above the waterline, and on the lid - that is, if I see them I get them out as soon as possible! Are they going to kill my fish? I have 6 flame tetras, 2 apple mystery snails and 2 bottom feeders.

Also, there’s a over growth of green algae, just splotches of green on the walls, I have a scrubber, but it keeps growing. Help me please!

Answer 1

It looks like some type of leech and there are about 500 types that live in water.

Some of them feed on the body fluids of snails and others feed on body fluids of fish or other animals that live in or come in contact with water.

It is impossible to identify it from your picture.

Another possibility is it might be a type of nematode. Some can be parasites of fish, while others live off bacteria and organic waste or on plants.

Nobody knows how many types of nematodes there are on our planet, but it is more than 2270 types on land and in water.

Sorry, but it is not possible to identify it without a lot more information. For now, I suggest you remove the ones you see and vacuum the gravel every time you do the weekly water changes (to get rid of the ones living in the gravel/sand).

Some predatory fish will eat them, so it is possible to get rid of the problem in a natural way.