External Parasite on Gem Tang?

[dtdream]

Hi, I've had my Gem Tang for almost 7 weeks coming 8 now, first 6 weeks is in perfect health, no issues whatsoever.

But for the past couple weeks I noticed that there is a white spot on the dorsal fin area of the fish. It comes and goes every couple days. At it's worst, the fish will have a tiny hole (I can kind of see through), but it heals up on its own after 2-3 days. Then after 2-3 days it comes back again. Fish is otherwise healthy (no other visible aliments, strong swimming, greedy feeder)

It was pretty hard to take photos, but I think I've got a fairly good shot this time. Looks like an external parasite but I can't be sure. No other fishes in my tank are affected, all seem healthy too. Water parameters are good (Nitrate less than 1ppm, phosphates less than 0.05, PH 8.3, Salinity 35ppt).

Can anyone advise what it is and what I should do?

 

[Jay Hemdal]

Did you treat the fish with anything as a preventative?
Just a thought - I wonder if this could be a single copepod that is causing damage that the fish is able to repair. Most parasitic copepods have a planktonic stage that can’t replicate in an aquarium. Barring any additional symptoms, I wouldn’t treat for this.
Jay

 

[dtdream]

Did you treat the fish with anything as a preventative?
Just a thought - I wonder if this could be a single copepod that is causing damage that the fish is able to repair. Most parasitic copepods have a planktonic stage that can’t replicate in an aquarium. Barring any additional symptoms, I wouldn’t treat for this.
Jay

Hi Jay, thanks for your reply as always.

No, did not do anything preventive. I did send this to a friend's QT with UV for 2 weeks, but it was just for observation. We decided not to do anything preventive as it was aggressively feeding and looked healthy from the get go (still is, bar the parasite looking thing).

So it's most probably a parasitic copepod? How long do you think it will stay like this assuming no treatment?

 

[Jay Hemdal]

Hi Jay, thanks for your reply as always.

No, did not do anything preventive. I did send this to a friend's QT with UV for 2 weeks, but it was just for observation. We decided not to do anything preventive as it was aggressively feeding and looked healthy from the get go (still is, bar the parasite looking thing).

So it's most probably a parasitic copepod? How long do you think it will stay like this assuming no treatment?

No - I can't say for sure if it is a copepod or not - it was just an idea. Female copepods will eventually develop egg cases that make them larger and more visible, but male copepods are pretty tough to see other than the chewing damage they can cause. If it is a copepod, it will eventually die, but I can't hazard to guess how long that will take.

Jay

 

[dtdream]

No - I can't say for sure if it is a copepod or not - it was just an idea. Female copepods will eventually develop egg cases that make them larger and more visible, but male copepods are pretty tough to see other than the chewing damage they can cause. If it is a copepod, it will eventually die, but I can't hazard to guess how long that will take.

Jay

Ah ok, but assuming it is a copepod, it should be safe to leave it alone?

And besides being a copepod, any other potential candidates for it? I understand it's just guesswork at this point, just trying to think of potential ways forward.

 

[Jay Hemdal]

Ah ok, but assuming it is a copepod, it should be safe to leave it alone?

And besides being a copepod, any other potential candidates for it? I understand it's just guesswork at this point, just trying to think of potential ways forward.

I guess it could also be a single fluke, but I would not expect to see fin damage come and go like that with flukes. Certainly if any new spots show up, that is a game changer, but for now, I don't see any clear treatment choice. As in human medicine, "First do no harm" is pretty important. You could dose the tank with Prazipro - that is generally safe, even for reef tanks, but it won't do anything for a copepod (it will help with flukes). If you go that route, just ensure you follow the label directions and be sure the tank has good aeration.

Jay

 

[dtdream]

I guess it could also be a single fluke, but I would not expect to see fin damage come and go like that with flukes. Certainly if any new spots show up, that is a game changer, but for now, I don't see any clear treatment choice. As in human medicine, "First do no harm" is pretty important. You could dose the tank with Prazipro - that is generally safe, even for reef tanks, but it won't do anything for a copepod (it will help with flukes). If you go that route, just ensure you follow the label directions and be sure the tank has good aeration.

Jay

Yea I was thinking of asking my friend who has a QT to help me do a Prazi treatment or maybe even cupramine, but wasn't sure if that was the right approach. He was suggesting using some sort of sharp object or even our own finger nail to try to see if we can scrape it off, but also, I'm not sure we should attempt that. Bit of a loss at the moment.

But ok, I suppose no harm to monitor for 2 weeks and see how it goes? Besides looking out for new spots, anything else I should be aware of/keeping an eye for?

And if it is a copepod, albeit a parasitic one, it sounds like I can't do much and is safe to just leave it alone and hope the copepod suffers an early death? lol..

 

[dtdream]

healed up on its own. will monitor if it comes back again.. very strange.

 

[dtdream]

andddddd... its back..

 

[Jay Hemdal]

andddddd... its back..

Is it in exactly the same location? If so, then I would begin to doubt that it is flukes or a copepod. Not sure what else it could be - perhaps a persistent bacterial infection? The fish still looks really good overall, so I would be hesitant about moving it to treat for anything.

Jay

 

[dtdream]

Is it in exactly the same location? If so, then I would begin to doubt that it is flukes or a copepod. Not sure what else it could be - perhaps a persistent bacterial infection? The fish still looks really good overall, so I would be hesitant about moving it to treat for anything.

Jay

Yes its in exactly the same location. this is the 4th time its appearing. yea the fish is otherwise healthy, eats well and pretty fat for a tang.

Could it be a hitchhiker parasite of some sort? I was trying to read as much as a I can but so far I can't find anything. Was thinking it might be a parasite similar to the "Cymothoidae parasite" which is said to " grip on their host for their whole adult life". Maybe a really tiny transparent one where I can't it when it's not attacking the fish, but when it starts attacking/eating the fish then I can see the "white spot". Its a wild guess at this point, but yea 100% confused.

 

[Jay Hemdal]

Yes its in exactly the same location. this is the 4th time its appearing. yea the fish is otherwise healthy, eats well and pretty fat for a tang.

Could it be a hitchhiker parasite of some sort? I was trying to read as much as a I can but so far I can't find anything. Was thinking it might be a parasite similar to the "Cymothoidae parasite" which is said to " grip on their host for their whole adult life". Maybe a really tiny transparent one where I can't it when it's not attacking the fish, but when it starts attacking/eating the fish then I can see the "white spot". Its a wild guess at this point, but yea 100% confused.

Cymothoids can move around, it wouldn’t expect them to stay in the exact spot like that….but that was my first thought. I’d also expect new ones to show up. Parasitic isopods like that are very difficult to treat - adults are killed with organophosphates at doses very close to, or even above, the lethal dose for fish. There are drugs that interfere with molting of the isopod, like dimilin, but they don’t kill adult isopods., only young growing ones.
In the absence of any other symptoms, I just can’t think of a safe treatment to try….
Jay

 

[dtdream]

Cymothoids can move around, it wouldn’t expect them to stay in the exact spot like that….but that was my first thought. I’d also expect new ones to show up. Parasitic isopods like that are very difficult to treat - adults are killed with organophosphates at doses very close to, or even above, the lethal dose for fish. There are drugs that interfere with molting of the isopod, like dimilin, but they don’t kill adult isopods., only young growing ones.
In the absence of any other symptoms, I just can’t think of a safe treatment to try….
Jay

Ok I suppose I'll just leave it alone continue to monitor as advised. but if does get worse or any other symptoms, will reach out to you again.

Thanks Jay!