This could be anything at this point. Things that come to mind areReedman said:... I bought the tank used and the tang came with it. I believe he was in the previous owners setup for two years. Was doing great until yesterday when my Azoo powerhead went crazy and burnt out...
- stress (from stray voltage)
- PCB poisoning (from the burnt wiring)
- "scared to death"
The fish may just be recovering from the sudden changes associated from removing the pump, but I would tend tothink more along the lines of PCB or related toxins from the windings in the pump "burning up". An immediate big (50%) water change, the use of Carbon, skimming like crazy (thin wet foam), adjusting the salinity daily while running the skimmer like this, and a big water change (another 50%) in about 3 days are all in order.
Good luck, hope this helps.