Fin Rot Or Tail Nipping?

[carina.]

Since I got my fancy guppies last Friday, I noticed their fins looked a little worn, I thought this was just the way their fins looked because I have seen them nipping at each other and chasing each other. Now i'm not so sure. All of my guppies' fins are slightly worn, and one of them has small holes in his fin now. How do I know if this is fin rot, or just the guppies being aggressive toward each other?


Tank size: 10 gallon
pH: 6.8
ammonia:0
nitrite:0
nitrate:0
tank temp:78
Volume and Frequency of water changes: 25% weekly
Tank inhabitants: Four fancy guppies, three black kuhli loaches

 

[Gytas]

what is the female to male ratio?
is there any other fish in the tank?

 

[carina.]

what is the female to male ratio?
is there any other fish in the tank?

They are all males, and there are only the four guppies and three black kuhli loaches.