Black mollie and tang tail rot?

[Miami Reef]

 

[Miami Reef]

The tangs completed copper, praziquantel, and metronidazole.

They are in observation with black mollies. The tangs have been getting ragged tails in QT and now the mollies have it.

Is this tail rot or aggression? Please help. Thank you.

 

[Miami Reef]

No one?

I’m checking here religiously hoping someone would have an answer.

 

[Jay Hemdal Verified Community Expert]

No one?

I’m checking here religiously hoping someone would have an answer.

Sorry - I missed your post.

I can't see the molly clearly, but IMO the tang has a bite mark on its caudal, not primary fin rot. I say this because the notch is pretty deep and angular. Fin rot, caused by bacteria, tends to erode the fin overall, not in sharp bands like that. However, I can't reconcile how this could happen with just the three fish in the tank. The one molly has no fin damage. When you see a group of fish that all have fin damage, but one does not, that is often the culprit. However, I would not expect a molly to be able to take a chunk of a fin like that (they can be nippy though).

Jay