Sick lionfish

[cool clown]

I need help yesterday morning my lionfish was acting weird. when I got home from work all the webbing between his fins and tail was gone and he looked ill the LFS had closed already so when I got up this morning he was dead. Did he get a disease? my other fish are fine. The lionfish is(was) by far the biggest fish in the tank. The others are tangs and damsles. I have been feeding him goldfish (just found out that this is extremley bad the guy at LFS said it was fine to feed him this). What I want to know is did this cause his death or do I need to treat the other fish and if so for what? Thanks

 

[cool clown]

No two days ago he was fine he is in the 80 the 180 I just bought 1 week ago(still have to finish stand and order filters then cycle it ). He had a slight discoloration he was a lighter coler but he would go darker after he ate and lighter when he had not eaten for a while. Their are 5 other small fish (1.5-2 inches) they all seem fine and eating well. There was nothing new added in the past month and that was a seabae anemone. I think it was an internal disease(liver or kidney) form the feeders. I have had him about 6 - 8 months.Thanks for any ideas on what happened. Like I said he has already passed I just don't want to lose anything else or have this happen again.

 

[michaeltx]

I have been feeding him goldfish (just found out that this is extremley bad the guy at LFS said it was fine to feed him this).
I did this on the first lion that I had before I know what I know now.
if the lion , puffer, or any SW fish for that matter their main diet is FW feeders it will cause a fat build up and cause sudden death on them. I lost 2 of them this way. also FW fish can harbor parasites and things that will kill the fish quickly because they have no deffence for it.
FW parasites can not live in SW but when the lion eats it swallows it whole so anything that is in the FW fish will never touch SW but will migrate into the fish.
general rule of thumb is if it is on the land or a body of FW DO NOT FEED it SW fish. FW feeders are used as a weaning food but not as a main staple for thier diet.
sorry for your lose.