Fluke? And if so, treatment? pics attached.

[Hal3134]

I just received a juvenile Naso tang from liveaquaria that has something on it's caudal fin. I'm guessing it is a fluke. It's brown, oval shaped, and about 4mm in length. Pics are below.

As part of my normal QT process I put it into a 30 min formalin bath followed by 45 min in methylene blue (Safety Stop part A and part B). I read that formalin normally takes care of flukes but this one is still attached.

I also tried to scrape it off with my fingernail, but that too was unsuccessful.

So, question #1: what is it?
question #2: what is the proper treatment.
question #3: why didn't the formalin take care of it?

I normally begin Prazi-pro on day 4 of the tank transfer method (2 days from now), but wonder whether I should accelerate that in view of the obvious.

 

[Frtdrmrose7]

I would do a FW dip and see if it drops off in that.

 

[Big G]

Dactylogyrus trematodes

These are a type of fluke or flatworm, but not one that we encounter every day. The usual treatments for flukes like Prazipro, General Cure, Freshwater dips and Formalin will all work for this.

 

[Hal3134]

So why didn't the 30 min formalin bath kill it?

And do I need to worry about other ones internally?

 

[Big G]

Great question. I'd consider the FW dip as the next course of action.

 

[wesman42]

So why didn't the 30 min formalin bath kill it?

And do I need to worry about other ones internally?

Microevolution is a very interesting topic that probably explains why it didn't drop off in the formalin bath. I'm not sure anyone would be able to give you a definitive answer.

I think you'll have more luck with the freshwater dip + prazi treatment. That sucker looks pretty big to me.

 

[Hal3134]

Just completed a 6 min RO bath with no effect. No change in color on the bug. It is still firmly affixed. I again tried to scrape it off with my fingernail, after the dip, with no luck.

 

[ngoodermuth]

I would try the prazi, all of the information I’ve found on trematodes lists praziquantel as the preferred treatment method.

Apparently these buggers can reside inside fish intestines as well, so if you haven’t already I would de-worm them internally as well by food soaking General cure + focus for at least 10 days.

 

[Hal3134]

Yes, Prazi-pro will be the next treatment. The first tank transfer is tomorrow (Sat) and I will add Prazi-pro to the water at that time unless someone tells me that the situation is more urgent than I think it is. If the Prazi doesn't work then I'm looking into metronidazole (API General Cure) next. The naso is eating, so I take that as a positive sign.

 

[ngoodermuth]

So, I asked a friend..

He thought it might be a species of parasitic crustacean, of the genus argulus.

https://www.nationalfishpharm.com/articles/argulus.html

NFP sells De-Los as one treatment option, another possible treatment would be Dimilin.

 

[Hal3134]

Thanks for the link. I'm still not sure what it is. It hasn't moved since I noticed it about 5 days ago. It also seems odd that it is affixed to the caudal fin. I would expect that a parasite would want to attach to the body of the fish where it is more fleshy with better bloodflow.

I started Prazi-pro on Saturday night and as of this morning (Monday) there doesn't seem to be any change in the parasite. I'm not sure how long it takes for Prazi-pro to work.

I didn't see the naso eat yesterday, despite feeding frozen brine shrimp. It also seems to be keeping its mouth open constantly. Not gaping, but open.

This was a fish from Diver's Den, so I've contacted liveaquaria to inform them of the situation. I don't expect to receive perfect fish, but this parasite was pretty obvious. Liveaquaria asked for pics which I will send shortly. We'll see what recommendations they have.

 

[ngoodermuth]

Prazipro kills flukes within 10 hours, and degrades by about 48 hours, so I'd expect some reaction by now if it was going to do something.

De-Los doesn't appear to be available any longer, but dimilin-x is if you would want to try that. Another thing to possibly try might be a fenbendazole bath, it's a dewormer used on prazi-resistant flukes.