Sick Fish - Can't solve the problem

[Jaws]

Just an update on this. All the fish have returned to good health and appetites are back to normal as well. Never did find the culprit but it must of been something in the water because water changes cleared it up. I've been monitoring the parameters too and they've been good. Re-added filter socks and haven't been changing them to help with biological filtration for now too. Thanks again for everyone's help.