Mandarin with white stuff on fin

[melev]

I have a mandarin with some white stuff that seemingly is ruining his side fin. Don't know for certain what it is, but I'm leaning toward lymphocystis. Looks kinda puffy like cotton, and the center of the fin is torn or gone. If I could get your input, and what you'd think would be a suitable way to treat this fish, I'd appreciate it. @melypr1985 @Humblefish

I've had this Mandarin since 2011, it's one of the ORA tank-raised fish...

 

[SashimiTurtle]

I'm gonna have to let the experts diagnose this. I had a fish with lymphocytes and it didn't look that bad. Just a few "cotton balls" on his pectoral fins. No loss of fin...

 

[Humblefish]

It does look like Lympho, although it is odd to see that on a dragonet. The ripped fin could be from the nodule getting snagged on the rock work. Unless you have a cleaner shrimp which has been picking at it? They will sometimes eat (or tear off) the nodule and aren't always too gentle about it.

Only other possibility I can think of is a bacterial disease of some sort, as fungus is rare in marine fish.

 

[Gweeds1980]

I would suggest that may be bacterial... the way it is right at the edge of the damage indicates its used a possible tear as an entry point.

Is he on frozen food? If so, plenty of good nutrition - selcon or similar. If live only, can you load the pods with selcon before feeding? Keep an eye on it, if it gets worse you may need to treat, but as long as he's healthy otherwise and feeding I wouldn't jump for the medicine cabinet.