Never seen this on a fish before, Help!!

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suzieScooter

Aquarium Advice Newbie
Joined
Jan 12, 2025
Messages
1
Location
Massachusetts
Wondering if anyone has seen this before? I am at a loss. I have had about 3 die offs in my brackish tank where my archer fishes, monos, and knight gobies have all died except 1 mono and one goby. The tank has been established for 3 years. This goby, I put into a quarantine tank and was the only one who had any visible lesions. 3 months ago he had one spot on one of his fins and then 1 month later it was on a couple fins and a white fuzzy spot on his side. The whole tank went through a triple treatment with maracyn oxy paracleanse and ich x and then another round of maracyn and ich X. The main tank seemed okay until I just had the third die off (now left with 1 mono and goby) with no fish displaying any lesions. The goby in quarantine is getting significantly worse although it is eating okay now. I have done a couple more treatments with ich X and the last a treatment with kanaplex and nitrofuracin green. I was thinking it was the brakish version of columnaris. I have finally been able to get a clear picture, so I would love any info someone might have for me. Even my local fish store is at a loss and has offered to humanely euthanize if and when I am ready for that (they know i would have a hard time doing that myself). At this point I am thinking of bombing the tank with bleach and reseting the whole tank.

Throughout this, I have lowered my temp to 72. And parameters are: salinity 1.005, pH 7.2, ammonia 0, nitrite 0, and nitrate 0. Main tank is the same except nitrates 0-5
 

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The white cottony piece on the tail could either be a fungal infection of a wound ( there appears to be some tail rot near it) or it's the virus Lymphocystis which is more common in brackish and saltwater fish. The other bumpy areas appear on the side look more a virus than bacterial or fungal. When you add it all together, whether the white fuzz is fungus or Lymphocystis, both point to the tank water being dirty. It may test okay ( it's rather unusual for a cycled brackish tank to have 0 nitrates without intervention btw.) but the proof is the disease. None of the meds you used will treat viral infections. In fact, most viral diseases are not curable in fish. If the fish is healthy enough, it can live with viral infections if the water remains clean. A healthy varied diet and good water change routine can help the fish's immune system to stay strong enough to keep the fish from succumbing to the virus and in time, the fish may recover. In the case of Lymphocystis, it spreads from ingestion so you want to keep the infected fish separated from any healthy fish. That's the medical part.

Now to the " how did they get it" part:
The fish most likely came to you already infected with the virus being dormant. That leads to what caused the fish's immune system to become compromised?
What is your maintenance routine?
How often do you change water?
What size tank is the main tank? What are you using for filtration?
What are you feeding the fish? How often? How much?
What are you using to remove nitrates?

Let's start there. (y)
 
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