Hi Guys,
I always hesitate to add my speculations to discussions like this. I don't think what we are dealing with is a Virus, but its just as likely a guess as my own. I have no hard facts on this. I just have my observations like everyone else here to go on. I will go out on a limb and mention though that I really think we aren't dealing with a pathogen. I haven't seen any evidence that shows its contagious. We haven't had fishrooms crashing or even multiple tanks in most cases where people report this. Again, I could be way off.. maybe there is a viral component. I'm not a microbiologist and have been out of a lab for far too long.
My thoughts on this are its not a pathogen at all, its a condition. Gas Bubble Disease. Its very well known condition that causes embolisms in fish when there is too much dissolved gas in the water. As Discus keepers we very commonly do huge water changes. Many of us "age" our water, which stabilizes it , but we are blowing off gases like CO2 there.. It can still be over saturated with other gases if you use too much air .. More isn't always better.
What got me on this train of thought was what happens here if I don't age my water... I do have alot of gas in my water.. Co2 mostly. I can easily create condition where I have a tank full juveniles darting and crashing and spinning out of control and dying, I have many times and thats why I limit myself to 30% tap. Its more pronounced in the smaller fish and I initially attributed to the dissolved gases covering their gills and irritating them or suffocating them. I did notice though that in my adults the response was varied. Some fish in the tank handle it fine. Others freak out and dart.. I have had some adults die in hours of a huge water changes. Again, thats why I use the 30% unaged wc now as a max, more with aged is fine. ... But this is when it gets interesting. The skittish darting doesn't end in a day....when the tanks water has aged over time.. It persists for several days.. which tells me that it may be internalized... and gas bubble embolisms.. also called gas bubble disease fits that. To further my point, I also noted in several fish that I could sometimes see small bubbles in their eyes and over time they would fade. .. possibly gas bubble disease? maybe, If this was to happen in the brain or other sensitive areas..I can see what may happen here.
So what else do we know. Its seems we see a spike in the winter.. thats generally when water is cooler and holds more gas .. But we also see a spike attributed to wilds and not just any wild.. this seasons wilds. Though its possible they are carrying a native virus, or picked something up from other fish, Its also possible that they have gas bubble disease from a combination of pressure changes in the airplanes and oxygen used in the shipping bags. > keep in mind Discus do not come from oxygen rich fast moving waters.. There may be combinations of factors that cause the condition here. When we see it Domestics... Its possible its from something similar if they are new stock,or recently imported. It can take days to weeks for the gas embolism to disappear.
I admit its a speculation on my part but when I seen what I have here with regards to water changes... If I stop doing water changes or drastically reduce them, the fish show no more symptoms after several days. It may very well be that our knee jerk reaction to do more water changes because our fish may be sick could actually be compounding a condition.
I would suggest anyone that has fish with this issue, get the fish to Dr. Smith here..
http://www.vetmed.vt.edu/people/bios/smiths.asp
He has an interest in Discus and is currently researching them and Cryptobia....who knows maybe that organism is involved... if not he may be the one that can look into your ideas on Virus, maybe even mine on Gas Bubble Disease. This Pathologist was a speaker at NADA 2016 and Is really very knowledgeable. It would be very worthwhile I think.
An option though rather indirect would be if you are having fish exhibit this condition, Try the no water changes or drastically reduced water changes for a week and see what happens. If its a virus, it will probably not matter either way. However, ifs its Gas Bubble disease as the Gas bubbles subside..the fishes behavior should drastically improve,Not sure the effect over filtration would have on this so thats a variable I can't account for.
Like I said, I have nothing scientific here but you may want to consider it and apply it to your conditions..
hth,
al
Gas bubble disease in fish..
https://www.ncbi.nlm.nih.gov/pubmed/9289892
http://www.agriculturejournals.cz/pu...les/216031.pdf
https://en.wikivet.net/Gas_Bubble_Disease
http://www.advancedaquarist.com/2014/8/fish
https://bettalatethannever.jimdo.com...ubble-disease/
....................................Theres a ton of information out there on This.......................