Yes, I am quite sure velvet is what I also mean, – its in my experience the one illness which paroes are phrone to, – and in particular wildcaught fish that has been under long periods of stress (or maybe other reasons) –
Normally paroes are quite strong and healthy fish and dont come down easy with illnesses. But odinium can occur. It shows up as small small dustlike particles on the sides and you can also see the fins being affected. If one fish has it, it will likely spread.
But its not a ‘bad’ bad disease, it can be cured, or stopped, or prevented, – but it can also disseappear, and then reappear.
I have found (as well as many others with paroes) that the one medicin that helps is spirohexol, – it really helps, – but lately I have not been able to obtain it in the small tablets that I usually have had. But maybe in the states you can still get it. Its worth while having.
http://www.seahorseaquariums.com/JBL-Spirohexol-20-Tablets//1510
This is the right one. Most shops now only have drops, and its really difficult to figure out how much for a small tank. I used the fluid once with not very good result. Tablets are better.
One tablet might cure a small tank.
But then, after that, good maintenance is important, – and sometimes a bit higher temperature can also be quite helpful. I dont know if this goes for all species, but I have had good results with p. linkei and slightly raised temperatures.
I think odinium comes when the fish is weakened, I think its possibly always present – but if weakened and in less optimal tank situation it might develop. Thats why I think wildcaught or commercial traded fish (long time in stressfull situations regarding water, food, tankmates etc) are more phrone to it.