[en7jos]

Worms that resemble lengths of thin white cotton wiggling in the water are normally just detritus worms and are harmless, if a bit unsightly and yucky. Many (most?) tanks seem have them (especially those with aqua soils) but they aren't noticed until there's a population explosion for some reason. Assume they've been there for a while and you've only just seen the tank in the right light / right time / etc to notice them. Some fish might find them a yummy meal, removal of food source can help, but I've had an outbreak in a never fed, new setup tank with Amazonia soil. Actually I've had short lived outbreaks in every tank I've setup with Amazonia, but only really noticeable in those tanks without fish to gobble them up! You might find they disappear as quickly as they appeared.

 

[en7jos]

Looks like you don't have any fish in your tank, going by the video? These worms were the final straw in me deciding to add micro rasborah to all my shrimp tanks. Natural part of the ecosystem maybe, nice to look at definitely not! Chemical treatments will surely do more harm than good, so it's a case of learning to appreciate their beauty or introducing some fish (at least temporarily) to eat them up. Probably never get rid of them completely, but I've not seen one in any of my tanks since shortly after adding the little fish. Either they've been eaten or else realised it is safest to stay hidden down in the substrate!

For Halloween this year I'm thinking of freaking out the kids by showing them what comes out in the tank after dark with a torch and big magnifying glass. All the little critters certainly gave me a shock when I first discovered them - especially the alien dragon fly nymph when that reared its head one night. Arrrggghhhhhhh!

I've been self medicating on "Foo the Flowerhorn" YouTube videos ever since and trying to absorb some of his appreciation for the beauty of the tank ecosystem as a whole, and not just the bits I intended to be there. But then in one of his latest videos I see that he nuked his volcano betta tank with just about every aquarium weapon to get rid of a plague of snails, so guess we all have our limits 0