Help identifying these worms!

[tinydot]

They start to appear after i switched my usual fish food from pellets to flakes, and after introducing nana plant tied to a driftwood.

Usually "invisible", but they swarm during water change, when i pour water into the tank. i wonder where do they hide at normal times.

How do i eradicate them completely?

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[coolgear101]

maybe you feed too much to your fish? I have encountered it before but after a few times of frequent wc, it disappears.

[boxedfish]

dario dario fish might help to keep them in check but will not eradicate them completely. the dario will die also if there's no more worm because they only eat live food and you are feeding flakes.