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Unidentified spiderweb lookalike algae ?


6 Jul 2023
Could someone help me identify those weird threads that grow in my tank ?

It's been two days that they are there in my tank when the light starts.

They look like spider web but more dirty ( like dust/detritus on them ) and more dark grey. They are very easy to remove and they broke into piece when I touch them.
I have some staghorn algae in the tank right now and they seem to like to attach themselves to it.
I'm not even sure it's algae.


There are a few aquatic spiders that build webs underwater, including the diving bell spider <Argyroneta aquatica>. They can give a nasty bite.

Filamentous bacteria can also form web like structures; I have seen this before in medical treatment tanks where the microbial balance shifts to allow them to fully colonise.
... and what about fungi? Is that possible?
Good question. I don't know. Aquatic fungi are often referred to as a "neglected class" that are simply "forgotten".
Mariyana Vatova (a key researcher in this field) is quoted as stating: "...many groups of aquatic fungi are poorly studied, and many species are yet to be discovered and described." <reference>
Aquatic fungi are often referred to as a "neglected class" that are simply "forgotten".
And yet, if I'm not mistaken, fungi are crucial for decomposition of matter rich is polysaccharides and poor in nutrients (wood, leaves, ...).
Ok so weirdly today I don't see anymore of it in the tank. It disappeared as fast as it came. But I don't want to talk to fast.

I looked more at it yesterday and it definitely didn't looked like algae, I would clearly lean toward it being bacteria or fungus.