Unknown Neurological Wrasse Disease (UNWD)

[Jay Hemdal Verified Community Expert]

Following. Always thought it was spinal or back injury

Likewise - prior to 2019, I thought the same thing. Then, after seeing some trends, I started to question it, and things just don't add up. The same thing happened with Uronema lesions. Literally everyone diagnosed those lesions as bacterial up until about 2005, when we did some skin scrapes and found it was Uronema.

Jay

 

[sc50964]

Likewise - prior to 2019, I thought the same thing. Then, after seeing some trends, I started to question it, and things just don't add up. The same thing happened with Uronema lesions. Literally everyone diagnosed those lesions as bacterial up until about 2005, when we did some skin scrapes and found it was Uronema.

Jay

I had a string of fairy wrasse death related to this issue about a year and half ago or maybe even longer. It was so common that I now have stopped getting fairy wrasses, especially the higher end ones like rhomboid, labouti, and lineatus. Don’t think I will ever shell out that much money for fish that have a high chance of getting this problem.

 

[Jay Hemdal Verified Community Expert]

I had a string of fairy wrasse death related to this issue about a year and half ago or maybe even longer. It was so common that I now have stopped getting fairy wrasses, especially the higher end ones like rhomboid, labouti, and lineatus. Don’t think I will ever shell out that much money for fish that have a high chance of getting this problem.

I wish I had good data on just how common this is. I stopped getting them at work because of the risk, but that also left me with no samples to send out for histopathology.....

Jay

 

[sc50964]

I wish I had good data on just how common this is. I stopped getting them at work because of the risk, but that also left me with no samples to send out for histopathology.....

Jay

This can’t be a natural problem that exists out in the ocean, right? You must have talked about that somewhere in this long thread. It must be related to stress due to captivity.

I also had a similar incident on a tilefish. I was trying to carefully catch it to move her out of QT but she just went crazy darting & slapping her tail even tho I got her pretty quick. She then showed up with a bent tail but was still able to swim with her tail pointing up. I thought that was similar to what the wrasses had so I was preparing for the worst. Then after a day or so, her tail injury healed and she went back to normal. That sort of convinced me that the wrasses were just too weak with their spine or back to recover but this thread is changing that.

 

[Jay Hemdal Verified Community Expert]

This can’t be a natural problem that exists out in the ocean, right? You must have talked about that somewhere in this long thread. It must be related to stress due to captivity.

I also had a similar incident on a tilefish. I was trying to carefully catch it to move her out of QT but she just went crazy darting & slapping her tail even tho I got her pretty quick. She then showed up with a bent tail but was still able to swim with her tail pointing up. I thought that was similar to what the wrasses had so I was preparing for the worst. Then after a day or so, her tail injury healed and she went back to normal. That sort of convinced me that the wrasses were just too weak with their spine or back to recover but this thread is changing that.

The trouble is, we’ll not likely see cases in the wild - affected fish would be eaten in a matter of minutes.
Jay

 

[sc50964]

The trouble is, we’ll not likely see cases in the wild - affected fish would be eaten in a matter of minutes.
Jay

Is there a consensus on if this new wrasses are susceptible to UNWD near their first 3 month or captivity or something like that?

 

[Jay Hemdal Verified Community Expert]

Is there a consensus on if this new wrasses are susceptible to UNWD near their first 3 month or captivity or something like that?

In public aquariums, it is most often seen in the first two months. Wholesalers/Importers don't seem to see it (or maybe they just don't admit it?) So - that seems to make a window of time where it is most commonly reported.

Sampling error comes into play here: usually just one fish is reported to be affected. That would at first, seem to rule out an infectious disease. However, hobbyists most often buy these fish one at a time, so there is that bias. I have one solid record of a public aquarium having a school of flasher wrasses affected. They sent samples out for histopathology, but they have not released the results (most likely going to publish a paper on it). The samples we sent out for histopath did not return any of the suspected viral agents....but it could be some other virus, or parasite.

Jay

 

[sc50964]

In public aquariums, it is most often seen in the first two months. Wholesalers/Importers don't seem to see it (or maybe they just don't admit it?) So - that seems to make a window of time where it is most commonly reported.

Sampling error comes into play here: usually just one fish is reported to be affected. That would at first, seem to rule out an infectious disease. However, hobbyists most often buy these fish one at a time, so there is that bias. I have one solid record of a public aquarium having a school of flasher wrasses affected. They sent samples out for histopathology, but they have not released the results (most likely going to publish a paper on it). The samples we sent out for histopath did not return any of the suspected viral agents....but it could be some other virus, or parasite.

Jay

Will it reveal any spinal cord damage or things like Flagellates & Uronema located there?

 

[Jay Hemdal Verified Community Expert]

Will it reveal any spinal cord damage or things like Flagellates & Uronema located there?

Yes - it will reveal any damage to the nerves, as well as the presence of parasites. Sometimes, it can be difficult to interpret the histo results - the pathologist tend to speak their own language, and then, while a veterinarian can read/understand the report, they often don't know fish well enough to apply that information. I find the best results come from a pathologist, veterinarian and fish husbandry person all working together.

Jay

 

[sc50964]

Yes - it will reveal any damage to the nerves, as well as the presence of parasites. Sometimes, it can be difficult to interpret the histo results - the pathologist tend to speak their own language, and then, while a veterinarian can read/understand the report, they often don't know fish well enough to apply that information. I find the best results come from a pathologist, veterinarian and fish husbandry person all working together.

Jay

Alright…, all eyes on that report then!!

 

[SinisterKestrel]

In public aquariums, it is most often seen in the first two months. Wholesalers/Importers don't seem to see it (or maybe they just don't admit it?) So - that seems to make a window of time where it is most commonly reported.

Sampling error comes into play here: usually just one fish is reported to be affected. That would at first, seem to rule out an infectious disease. However, hobbyists most often buy these fish one at a time, so there is that bias. I have one solid record of a public aquarium having a school of flasher wrasses affected. They sent samples out for histopathology, but they have not released the results (most likely going to publish a paper on it). The samples we sent out for histopath did not return any of the suspected viral agents....but it could be some other virus, or parasite.

Jay

Jay,

I was wondering if this study had come up at all in your research of this topic

Some Environmental Contaminants Influence Motor and Feeding Behaviors in the Ornate Wrasse (Thalassoma pavo) via Distinct Cerebral Histamine Receptor Subtypes​

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1310913/

doi:10.1289/ehp.7983

Particularly of the noted neurodegenrative symptoms re: Cadmium exposure, do align closes with the cases ive seen and that are noted in this thread, not to suggest cadmium is to blame for these instances, but I do wonder if a similar heavy metal or industrial contaminant, bioaccumulated or biomagnified, could contribute to this, hence why onset may be delayed and seemingly random.

I would also think the histopathology wouldn't generally turn this up unless you were to be specifically looking for it?

 

[Jay Hemdal Verified Community Expert]

Jay,

I was wondering if this study had come up at all in your research of this topic

Some Environmental Contaminants Influence Motor and Feeding Behaviors in the Ornate Wrasse (Thalassoma pavo) via Distinct Cerebral Histamine Receptor Subtypes​

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1310913/

doi:10.1289/ehp.7983

Particularly of the noted neurodegenrative symptoms re: Cadmium exposure, do align closes with the cases ive seen and that are noted in this thread, not to suggest cadmium is to blame for these instances, but I do wonder if a similar heavy metal or industrial contaminant, bioaccumulated or biomagnified, could contribute to this, hence why onset may be delayed and seemingly random.

I would also think the histopathology wouldn't generally turn this up unless you were to be specifically looking for it?

Thanks,

From the abstract (I'm in a rush and couldn't read the whole article) it looks like the neurological symptoms were combined with a reduced feeding response. I've been using a "continued feeding response" as the symptom of note in these cases, so that doesn't match up.

If it were heavy metal toxicity, I would expect to see invertebrates affected first and to a higher degree, yet that hasn't been noted - only wrasses develop clear symptoms.

I must say though, that this is an odd study! T. pavo is not a common study fish, and why they chose that species and exposed it to spiked cadmium is a really odd choice IMO.

Jay

 

[SinisterKestrel]

Thanks,

From the abstract (I'm in a rush and couldn't read the whole article) it looks like the neurological symptoms were combined with a reduced feeding response. I've been using a "continued feeding response" as the symptom of note in these cases, so that doesn't match up.

If it were heavy metal toxicity, I would expect to see invertebrates affected first and to a higher degree, yet that hasn't been noted - only wrasses develop clear symptoms.

I must say though, that this is an odd study! T. pavo is not a common study fish, and why they chose that species and exposed it to spiked cadmium is a really odd choice IMO.

Jay

Jay,

Thank you for your response, they way I interpreted the results of the study was the feeding response reduction was noted with exposure to the pesticide endosulfan, not as much with the cadmium exposure.

"Fish treated with Cd at 11.32 mg/L exhibited greater (p < 0.001; Figure 1A) hyperactive swimming activities such as moving in only a vertical direction and/or “bumping” against each other or against the glass tanks, in contrast to controls, which were often inactive and spent most of their time along the bottom of the tank. Fish treated with a concentration of 2.26 mg/L Cd displayed only moderate stereotype behaviors (Figure 1B), including hyperactive movements that consisted of swimming mainly in a vertical direction toward the surface of the water, whereas controls exhibited more random movements. Conversely, endosulfan caused a significant increase of some hyperactive movements (p < 0.05; Figure 1A,B) such as swimming in a vertical direction, whereas “bumping” type of swimming behaviors occurred in a less significant manner. This pesticide markedly reduced feeding, even at the lower concentration (0.2 μg/L)."

I was thinking about the possibility of the wrasse being exposed to low levels of something prior to collection (again I don't see either cadmium or endosulfan being the culprit or particularly relevant here, but a different neurotoxic agent certainly could, possibly levels biomagnified via their diet over long periods of time, a mercury in tuna situation) causing long term or sudden onset neurodegenrative symptoms in a percentage of the import population.

The study also focuses a lot on histamine pathways and the histaminergic impact of these neurotoxins, if the viral hypothesis is correct is it also possible the culprit produced a similar histaminergic impact?

Additionally I've seen lots of people postulate stress factors involved, stress is a significant endocrine disrupter, I could also see that contributing to neurodegenrative issues.

(My apologies this reply is way longer and more rambling than I intended)

 

[Jay Hemdal Verified Community Expert]

Jay,

Thank you for your response, they way I interpreted the results of the study was the feeding response reduction was noted with exposure to the pesticide endosulfan, not as much with the cadmium exposure.

"Fish treated with Cd at 11.32 mg/L exhibited greater (p < 0.001; Figure 1A) hyperactive swimming activities such as moving in only a vertical direction and/or “bumping” against each other or against the glass tanks, in contrast to controls, which were often inactive and spent most of their time along the bottom of the tank. Fish treated with a concentration of 2.26 mg/L Cd displayed only moderate stereotype behaviors (Figure 1B), including hyperactive movements that consisted of swimming mainly in a vertical direction toward the surface of the water, whereas controls exhibited more random movements. Conversely, endosulfan caused a significant increase of some hyperactive movements (p < 0.05; Figure 1A,B) such as swimming in a vertical direction, whereas “bumping” type of swimming behaviors occurred in a less significant manner. This pesticide markedly reduced feeding, even at the lower concentration (0.2 μg/L)."

I was thinking about the possibility of the wrasse being exposed to low levels of something prior to collection (again I don't see either cadmium or endosulfan being the culprit or particularly relevant here, but a different neurotoxic agent certainly could, possibly levels biomagnified via their diet over long periods of time, a mercury in tuna situation) causing long term or sudden onset neurodegenrative symptoms in a percentage of the import population.

The study also focuses a lot on histamine pathways and the histaminergic impact of these neurotoxins, if the viral hypothesis is correct is it also possible the culprit produced a similar histaminergic impact?

Additionally I've seen lots of people postulate stress factors involved, stress is a significant endocrine disrupter, I could also see that contributing to neurodegenrative issues.

(My apologies this reply is way longer and more rambling than I intended)

Oh, and another aspect I should have mentioned - this syndrome has been restricted to fairy and flasher wrasses. I have had a couple of reports from yellow Halichoeres wrasse, but none from this genus.

Jay

 

[Xanthurum]

I recently got 3 wrasses. A Rhomboid, Pintail and a McCoskers. After a week in QT the Pintail started showing signs of this today. I moved him from the QT to my fuge on my DT because I didn’t want any of the other fish in the QT to possible cause it any harm. A bit risky given he hadn’t completed quarantine but it was one I was willing to take. He has been eating pods like crazy but still swimming aimlessly.

I guess it will be interesting to see if any of the other fish especially the other 2 wrasses start to show signs. If the Pintail can be of any scientific use let me know.

 

[Jay Hemdal Verified Community Expert]

I recently got 3 wrasses. A Rhomboid, Pintail and a McCoskers. After a week in QT the Pintail started showing signs of this today. I moved him from the QT to my fuge on my DT because I didn’t want any of the other fish in the QT to possible cause it any harm. A bit risky given he hadn’t completed quarantine but it was one I was willing to take. He has been eating pods like crazy but still swimming aimlessly.

I guess it will be interesting to see if any of the other fish especially the other 2 wrasses start to show signs. If the Pintail can be of any scientific use let me know.

Any signs of trauma on the head of the pintail?

Please keep us updated - it’s subjective, but the more information we get, the more we know about this issue.

Jay

 

[Xanthurum]

Not that I saw but there was some minor damage to its tail. Not sure if it was being harassed before or after he started showing signs. The damage is very minimal like only one nip from a tankmate. He is still very responsive, when I approach he comes to the front of the fuge but it’s obvious swimming is difficult and is still gobbling as many pods as he can.

 

[Xanthurum]

He made it through the night but is having more difficulty swimming today. Still interested in food and responds when I approach but I’m pretty sure it’s just a matter of time.

 

[Xanthurum]

Short video of the pintail, the Rhomboid and McCoskers both seem just fine in the QT today. The fuge that the Pintail is in is about 35 gallons and has very little flow so it’s not tumbling around due to flow. I don’t have a flow sensor on it but I’d say it’s half of what the QT has and that only has a hang on AquaClear 30.

 

[Xanthurum]

Just in case it helps the Pintail did not make it. I have not seen him since the day the video was taken. My fuge is full of rock so I’m sure he is bristle worm food by now.