is this Brook in my Juvenile clownfish

Johnny Walker · Mar 25, 2026

So ive had this tank for roughly 2.5 months, cycled after 5 weeks and added 2 clowns after that. 2 weeks later i added a royal gramma. I discovered my overflow box was leaking and had a massive crack in it. While the one was on order i only had 40% of my display tank volume. My ammonia read 0 the entire time, my salinity is ~35 PPT(during the lifeboat mode it had crept up to ~36.2 over the 10 days, for some reason the ATO wasnt keeping up?). about 5 or 6 days into this "lifeboat" mode, my royal gramma died.he showed some signs of oxygen distress, then died overnight(ive included a picture of him as he may have had a pre-existing injury when i got him, hopefully its not the sign of a parasite, ive included a picture).I had an in tank filter running during this time with plenty of splashing for gas exchange. On monday i received my new overflow box(about 10 days without the sump hooked up) I plumbed everything back in. I took that opportunity to add another bag of sand to the tank(caribsea arag-alive). the tank clouded up, but everything had cleared up by tuesday morning. This morning my 1 Clown did not eat. and under the blue lights it looks like there is a bit of extra mucus on them? I was wondering if this is something like brook, or if its a stress response from having too many changes to their environment in too short of a period.

I know AI is not great for alot of this stuff, but 1 ai is telling me its brook forsure and another is telling me its not. So i thought i would come to the experts. Please let me know if more information is required.

Thanks in Advance.

vetteguy53081 · Mar 25, 2026

Johnny Walker said:
So ive had this tank for roughly 2.5 months, cycled after 5 weeks and added 2 clowns after that. 2 weeks later i added a royal gramma. I discovered my overflow box was leaking and had a massive crack in it. While the one was on order i only had 40% of my display tank volume. My ammonia read 0 the entire time, my salinity is ~35 PPT(during the lifeboat mode it had crept up to ~36.2 over the 10 days, for some reason the ATO wasnt keeping up?). about 5 or 6 days into this "lifeboat" mode, my royal gramma died.he showed some signs of oxygen distress, then died overnight(ive included a picture of him as he may have had a pre-existing injury when i got him, hopefully its not the sign of a parasite, ive included a picture).I had an in tank filter running during this time with plenty of splashing for gas exchange. On monday i received my new overflow box(about 10 days without the sump hooked up) I plumbed everything back in. I took that opportunity to add another bag of sand to the tank(caribsea arag-alive). the tank clouded up, but everything had cleared up by tuesday morning. This morning my 1 Clown did not eat. and under the blue lights it looks like there is a bit of extra mucus on them? I was wondering if this is something like brook, or if its a stress response from having too many changes to their environment in too short of a period.

I know AI is not great for alot of this stuff, but 1 ai is telling me its brook forsure and another is telling me its not. So i thought i would come to the experts. Please let me know if more information is required.

Thanks in Advance.

Yes, does look like brook. 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.
Since a formalin solution is often not available for use, 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.

Johnny Walker · Mar 25, 2026

Im in Canada im not sure what is available but i will get to the LFS and see what they have. I have an extra tank i can setup as a quarantene atleast.

thx for the quick reply