Possibly bacterial infection?

[Ctg0209]

So I’ve had this yellow tang in QT for a little over a month battling black ich. I dosed prazipro once a week for 3 weeks and it kept coming back so I dosed every 3 days (today was the third dose) and it’s not as bad but still present. Today though I noticed a dark spot on his top fin. I’m thinking it’s a bacterial infection but was wondering if someone could confirm. I am also trying to figure out if I should dose some antibiotics or is it the stress of being in qt for so long causing this? Thanks in advance

 

[HotRocks]

Need a more up close picture with better lighting.

@Humblefish has encountered some prazi resistant black ich recently. You may have to use hypo or formalin to rid it.

If you can get a better picture we can probably help you determine what you are dealing with.

 

[Humblefish]

I've also encountered scarring from turbellarians (black ich). It still looks like a dot or two is present, but the skin scrape comes back clean.

 

[Ctg0209]

Need a more up close picture with better lighting.

@Humblefish has encountered some prazi resistant black ich recently. You may have to use hypo or formalin to rid it.

If you can get a better picture we can probably help you determine what you are dealing with.

 

[Ctg0209]

Disregard the white spots...dirty glass

 

[Humblefish]

Is it near the eye? That could be HLLE: https://www.reef2reef.com/threads/hlle-head-lateral-line-erosion.259916/

 

[Ctg0209]

Yea there are some spots on top of the eye. I was more concerned with the redness on the top fin

 

[Humblefish]

I was more concerned with the redness on the top fin

I'm not really seeing it in the pic, but redness in a YT usually means 1 of 2 things:

1. Sudden swing in tank salinity
2. Bacterial infection: https://www.reef2reef.com/ams/tank-terror-bacterial-infections-in-the-reef-tank.22/