The question is, which meds? It could be velvet. It could also be a gram negative bacteria infection imo. The problem is if you start treating for one and guess wrong it will do more harm than good and delay the proper treatment. I don't know of any way to safely treat for both at the same time.
I don't know why I even bother.
Yea actually. It could have been white now that I think about it. It was just a really think layer.
Yours is a reasonable guess based on how quick it seems to be acting. It just doesn't have the characteristic visual signals of Velvet and the fish aren't displaying the behavioral symptoms of hiding or swimming into strong flow. It gets even more complicated by the likely presence of flukes.
Flukes tend to be very small as shown in the posts toward the start of this thread. Unless you hold them against a dark background it can be hard to see them clearly. You will eventually need to treat the flukes with Prazipro or a formalin bath. For now, the fresh water dip should help with the flukes and it will also help with velvet so I would catch and dip all of your fish. Getting a QT set up would really be helpful at this point if you haven't already.
I have had fish in the same tank all die with in hours of each other. More than one tank too. Every fish in these tanks acted different and some showed no signs of being sick at all, but they all died.
I believe that pic was for a reference to see if that is what he saw.
