Any ideas what this might be?

[leebca]

Not without a better photo or additional symptoms.

[CRJDriver]

How long should the fish play dead after the freshwater bath? Gave him a freshwater dip under instruction from the LFS. Got a bag, filled it with RO water, put in the display tank to get temperature accurate. Filled the QT tank with display tank water, left the fish in the bag for 3-4 min, netted out, put in the QT tank. Now the fish is sitting on the bottom, but still breathing. It did play dead while in the dip, but showed no signs of a fatal dip. So the question is....how long will it "play" dead before it will act normal again? The light is off, but I'd like to turn it back on to try and feed him tonight. Good or bad idea? Should i just wait to see if he's still swimming tomorrow and try then?

[leebca]

Compare what you did with how it should have been done: Freshwater Dip for Marine Fishes

If the pH wasn't controlled, I'm surprised the fish isn't already dead. It is probably in shock right now. You can pray and keep the lights off.

With so much good experience and knowledge here at Reefland, I'd recommend running by any LFS proposed fish treatment by those who help out in these Forums before actually do it.

[CRJDriver]

Compare what you did with how it should have been done: Freshwater Dip for Marine Fishes

The only difference is I used a bag instead of going to buy two identical containers and the medication.

[leebca]

What was the pH and how did you measure it?

Is the fish any better today?