Disease identification

SandersReef · Jun 20, 2026

Hi all,
Yesterday my clownfish suddenly showed white coating on the skin and fin rot. The fish declined very fast and unfortunatelly i found him dead this morning. Other fish do not show symptoms on the skin, but seem a bit stressed and an increase in breathing. Which disease am i dealing with? Other fish are still eating.

vetteguy53081 · Jun 20, 2026

This fish has Brooklynella. The most significant sign is the amount of slime on its body which is noticeable on the fish. This mucus generally starts at the facial area as well as gills and spreads across the body producing lesions as it progresses often confused with ich and can turn into secondary bacteria. Other symptoms will be lethargic behavior, refusing to eat and heavy breathing from the mucus.
Start with a prolonged 60 minute bath of ruby rally pro then at a lower concentration in a quarantine tank. The longer the fish are exposed to the treatment, the more effective it will be at eliminating this issue.
Temporary relief can be achieved by giving the fish a FW bath or dip in water same temperature as display tank. Even though this treatment will not cure the disease, it can help to remove some of the parasites, as well as reduce the amount of mucus in the gills to assist with respiration problems.
Treatment is best done in a QT tank using either quick cure (more effective but now harder to find) or Ruby Rally Pro. Ruby takes a little longer and initial treatment generally takes 2-3 days to really start going to work.

Jay Hemdal · Jun 20, 2026

SandersReef said:
Hi all,
Yesterday my clownfish suddenly showed white coating on the skin and fin rot. The fish declined very fast and unfortunatelly i found him dead this morning. Other fish do not show symptoms on the skin, but seem a bit stressed and an increase in breathing. Which disease am i dealing with? Other fish are still eating.

It's difficult to say from the photos, it could be Brooklynella, but the fish also has damaged fins, from another fish attacking it, not from fin rot.

What other fish are in this tank?
How long did you have this clownfish?