Is it possible to get any pics from the side of the fish/tank?
Any unusual behavior? Flashing? Gasping?
EDIT: Oh, I see that you mentioned no flashing.
Well, usually flashing is witnessed before any visible external skin/slime coat symptoms. And velvet usually has a golden sheen to it and the spots are smaller in size than ich cysts.
Did all this sudden loss of color and slime coat/lumps happen within 24 hours?
I am thinking it was just irritated/partially poisoned by the dosing the ferts right next to it, as they are somewhat sensitive fish, especially to copper which is in flourish comp.
Not sure what you could do to help it any. I don't know if dosing Melafix or Prime will help at all with the slime coat. Don't know if salt baths or making the water brackish will help it overcome this slight intoxication. Maybe Indian Almond Leaves or Alder Cones or similar will help him.
No, no other sighs of stress/unusual behavior or disease aside for this.. stuff
on him. He's not lost any color but the unidentified stuff on top of him makes his markings looking fainter/duller (only seems to be on the top/sides near top of the body. Belly and lower sides are unaffected and still a vibrant yellow-orange and black-brown (stripe/spot) that a male puffer should have). No shine from the stuff on him, its dull. I'm not entirely sure if it was 24 hours or longer to appear. He was fasted (not fed) for roughly 48 hours since he got supper fat after last feeding + hunting some snails in tank and I wanted to avoid constipation issues so I wasn't looking at him for about 2 days. I noticed when feeding yesterday, and took photos to post the thread immediately.
Cherry shrimp and otos still show no signs today of any issues (but the tank is on a minimum 4 week lock down and observation.. which sucks as I was just planning to get new plants and rescape it ugh!).
I moved the dwarf puffer to a 10g qt tank to monitor/get away from ferts (if that's a possible cause) and treat if I ever figure out what he has needs treatment. Since he's hide based not scale I'll have to look carefully at medication options to ensure I don't use something that may harm him.
Its near impossible to observe him, he's extremely skittish of me after catching and moving him last night so I can't really tell the state his skin is in right now >.<