Second opinion sought on diagnosis and treatment plan

[jelazar]

I'm storing a bunch of fish for a friend in a big rubbermaid stock tank. A pair of mostly-black clowns host near the surface, and yesterday I noticed they looked kinda filmy. They don't present other symptoms. Tankmates include several tangs, hawkfish, anthias, and a wrasse. The male lyretail is active but isn't as hungry as usual. Otherwise the fish appear normal.

I pulled the clowns out this evening to take pics and look more closely. Based on presentation and lack of other symptoms, my guess is brook but I suppose it could also be velvet. Your thoughts?







I performed a 45 minute aerated formalin dip and the clowns tolerated it well. The bottle calls for 0.1ml per gallon, which doesn't sound like much.

 

[melypr1985]

it's hard to say either way. Are they breathing heavily? Can you pull a tang or that anthia for a closer look? That might help with diagnosis. It stinks, but brook and velvet can sometimes look so similar.

 

[jelazar]

They're not breathing heavy, flashing, or swimming into the current. I'll see about pulling the anthia, but I expect trouble.

I also have a hobby-grade microscope, but I've never tried to take a sample from a fish.

 

[melypr1985]

They're not breathing heavy, flashing, or swimming into the current. I'll see about pulling the anthia, but I expect trouble.

I also have a hobby-grade microscope, but I've never tried to take a sample from a fish.

I would pull at least a couple fish (that you can catch) to get a closer look at them. Odds are that brook will only effect a few of the fish where velvet will be on all of them. That should help. Though you can address both parasites easily with treatment for velvet.

Acriflavin dip followed by copper. Add in metroplex for a couple weeks during copper treatment and you have both covered all around.

 

[jelazar]

I performed a 45 minute aerated formalin dip and the clowns tolerated it well. The bottle calls for 0.1ml per gallon, which doesn't sound like much.

The more I thought about this, the more this formalin dosage seemed too small. The bottle is 37%, and called for 1 ml/18 gallons. That works out to 1 drop per gallon of water. That just can't be strong enough.

So I compared this to Formalin-MS, which is also 37%. Formalin-MS says:
"Use 2 drops per gallon of aquarium water every other day until control is achieved.
To use as a dip:
Use 20 drops per gallon and treat fish for a maximum of 50 minutes. Remove from dip sooner if fish shows signs of stress."

So it's clear to me that 1-2 drops per gallon is correct if you're adding it to a QT. But for a standard ~45 minute dip, MS recommends 20 drops (~1ml), which is 10x the dosage printed on my bottle of formalin.

I redipped the clowns tonight in the stronger dosage. They tolerated the dip well. The first, understrength dip on Monday didn't seem to make a difference. I'm hoping to see some signs of improvement after tonight's full-strength dip.

I also have a hobby-grade microscope, but I've never tried to take a sample from a fish.

The male anthia was dead Tuesday afternoon. I snipped a gill sample and put it under the microscope, but I couldn't be sure what I was looking at. I also did a skin scrape of the female clown and looked at that. There were lots of teeny black specks swarming around, but nothing I could identify. The clowns are both acting normally but still have a slight slime to them. The last female anthia was dead this afternoon.

 

[Humblefish]

Sometimes even a small dosage of formaldehyde (formalin) will clear brook, but velvet requires followup CP or copper treatment.

Did the fish go right back into the same QT they were taken out of? If so, they were likely reinfected with brook anyway.