Question About Fin/tail Rot

[shbimi]

About 3 days ago i noticed one of my male (i have two) guppies had jagged edges around its tail, but only slightly. Kept an eye on him yesterday and noticed another, this time a rip. Last night there were no more signs, but this morning i've woken up to find a deep and wide rip, about half way down his tail and 2-3mm wide.

Can fin rot spread this quickly, or do i have a nipper in my tank?

There are only guppies in there.

 

[Sterbai]

About 3 days ago i noticed one of my male (i have two) guppies had jagged edges around its tail, but only slightly. Kept an eye on him yesterday and noticed another, this time a rip. Last night there were no more signs, but this morning i've woken up to find a deep and wide rip, about half way down his tail and 2-3mm wide.

Can fin rot spread this quickly, or do i have a nipper in my tank?

There are only guppies in there.

I can't confirm guppies nip guppies for definate BUT I have seen my orange guppy go after the blues biting at their bodies. However I have other fish in my tank so it could have been them that keep causing the damage.

 

[WILDER]

Size of tank in gallons or litres.
How many fish and which type.
Water stats in ammonia, nitrite, nitrate, and ph.

Any red streaking on red eges to the tail.
I would add some myxazin to the tank by waterlife.