I have another theory on what's going on here.
Scenario... Purchased 9 common wrasses online. Box arrived overnight, well packed and at a reasonable temperature. Matched salinity and temp. Copper Power at around 0.75ppm. Measured bag copper at 0.25 (Cupramine) . Straight in thus no real risk of ammonia toxicity.
Day 1 - Start 4 day ramp to 2.0 Copper Power, Metro, etc...
Day 2 - Lost 1 wrasse. No obvious cause of death. Skin scrape and microscope did not provide any answers. (I'm somewhat new with microscopy so there is room for error)
Day 4 - Lost the second wrasse. This one had obvious red marks telling me that it was Uronema. Still did not detect anything under the microscope, but again... It's a new tool for me.
Day 5 - I took a sample of detritus from the tank... this time it was entirely obvious. The detritus was infested with Uronema.
Day 10 ish - Pintail wrasse starts displaying signs of UNWD. See linked videos.
This qt tank has 50 gallons of water but it's a 75 gallon tank. There is around 8 inches from the water surface to the top. I also have neoprene padding under the eurobrace. I would put the likelyhood that this is an impact injury from jumping at pretty close to zero. I suppose it might have darted into the side glass. That's possible, but I don't think so.
My theory is that this is Uronema infecting the brain or some aspect of the spinal column.
Why is it more common now than it was historically?
I imagine that in years gone past, Uronema was somewhat rare whereas nowadays pretty much every fish that I buy, from any source, seems to come with Uronema. At least amongst the commonly affected species but I suspect that it lingers in other fish that are less susceptible. It's now almost certainly in all of the supply chain water whereas historically, that might not have been the case.
Why only new fish?
Wrasse's can live and be healthy with Uronema in the tank, but if they are stressed they become susceptible to the parasite. This is most likely to happen in supply chain, quarantine, or the first couple of months in the display. Most wrasses are likely exposed during supply chain and come to the hobbyist as a carrier. In some rare cases they might make it into the display tank before being exposed at which point it might take a month or two for UNWD to present.
I don't think that it can be said that UNWD never presents when a wrasse has been in a display tank for over 6+ months. It's likely somewhat rare and the hobbyist might assume a spinal injury or that the fish went crazy with old age. The point being, that it is probably under reported in well acclimated specimens.
Why is it seemingly not contagious?
Uronema is contagious but some fish specimens are healthier or just generally hardier than others and can keep it at bay. A second fish might one day succumb to UNWD and it might be assumed that this was transmitted from the first wrasse, that the virus lay dormant, but really it's ubiquitous in the tank and the second wrasse was just a bit hardier and managed to keep it at bay a bit longer.
Why doesn't Uronema always kill the same way?
I know for certain that some wrasses succumb to Uronema and have no visible signs of it. Other times, the red spots are noticeable. If red spots do present, they are not always in the same place.
Uronema is having it's way with the fishes. It gets internal and starts multiplying inside the fish. It digs in deep and when it pushes outward the red spots appear. That's game over for the fish.
Uronema will kill most wrasses before it gets to the brain or the spinal cord. However, in some cases, perhaps it finds a more direct path and infects an area of the nervous system that causes the behavior that we are observing.
Could it be a virus?
Yes - of course. Mine is only a theory. However, if it is a virus, it is a virus that is causing a neurological disorder and it is odd that it only seems to affect wrasses? I'm aware of the virus that affects only cardinals, but I have to believe that viruses that are super selective are somewhat rare; whereas I am pretty sure that Uronema is in just about every tank.
I supposed that begs the question... If this is Uronema, why does it only affect wrasses in this way and not anthias (for example). I can't answer that. It must have something to do with the physiology of wrasses.
The biggest problem with the virus theory is the low contagion rate. A healthy immune system could explain this in the same way that it explains why many fish can fight off Uronema, but now we have an unknown virus, that's really not very contagious at all, that causes a neurological disorder, affects only wrasses, and that the majority of wrasses (95%) can fight off. It's new in that it is only now being documented. I completely agree that this is possible but it's not a simple explination.
Or it could be a known pathogen that is probably in 99% of our tanks and attacks from inside the fish. It's known to spread internally and perhaps 5% of time it happens to reach an area of the fishes nervous system that results in the odd behavior and subsequent mortality that we see.
I don't know what's going on. I do know that I've lost 30% of my wrasses to Uronema of which one displayed the symptoms of UNWD.
Uronema is brutal. I don't know how to qt for it. You would have to isolate every fish and euthanize any where the parasite is found. I'm pretty sure that any fish can be a carrier - if only intermittently - thus the wait time to be certain that the fish is not a carrier would be unmanageable. If someone patents a cure for Uronema, they will be rich for sure and I will gladly support them. QTing for Uronema might have been possible in years gone by, but not if every fish that touches any aspect of supply chain must be assumed to have come in contact with it. I wonder how many mysterious fish deaths have really been Uronema. I imagine it's a lot.
