Partial tank crash

[jarrid]

So I noticed that one of my triggers had a whit spot on his eye and on his body, so I medicated the whole 75 gallon tank w some artemiss microbe lift and followed the directions to turn off the protein skimmer and uv filter. About 6 hours after I did this I noticed two of my triggers were dead along with two of my puffers. One trigger along w a snowflake eel, a frogfish and two giant hermit crabs lived. As soon as I noticed the dead fish I immediately plugged my uv filter and protein skimmer back in. So far so good, but the frog fish isn't looking so good. Any idea what happened or what is goon on ? Howcome only some of the fish died while others have lived ? Any help would be greatly apreciated.