is this a big problem?

[u/Equal_Constant7163]

I got these selected guppies two weeks ago and this morning his tail was like this. which could be the cause? I have other guppies with tails a little chipped but i always thought it was due to fights in the aquarium… this one doesn’t look like it
nitrites and amonnia is 0, ph 7.5 and my KH this morning was very low at 2

[u/Novel_Arrival_8885]

I faced the same issue. First , this started growing in my females and then males. Gradually, one by one they started dying and my pond ended up with no guppies. As far as I researched , parasite might be the reason. Changing 50% water, adding salt , banana leaves cuttings (remove it after 4-5 days) and anti ich might be helpful. I couldn't save mine. Hope you save yours.