Red on tip of guppy tail

[johnnyboyoc]

Hey, I noticed since yesterday there is red on the tip of my guppy's tail. Just finished treating my tanks for parasites a couple of day before so I don't think it is that, also my water seems pretty clean with regular water changes. Behavior is normal. Any thoughts?

 

[johnnyboyoc]

actually might be ammonia levels. Carbon pack was out during parasite treatment, so could have went up during that time.