new fish/ problems

ok so i just got rid of a 12 in. pacu from my 55 gallon and added a 4 in. pangasius catfish. in the tank also are a 4.5 in. oscar, 4 in. Jack Dempsey, 2 in. convict cichlid, and 2 in. common pleco. after the first day, the water fogged up pretty bad and the catfish wont eat anything i have offered. i also noticed a white spot on each of the pangasius' fins. what is going on? what should i do? keep in mind this tank is a growout tank and i am getting a 125 in a few months and will be trading the pangasius back to my LFS when he gets too big, so dont lecture me on how big they get ;) i know.

please reply!

I'm definitelty not a pro or anything, but I'll try and help.
I have a couple questions,
1. did you quarantine the pangasius catfish before adding him? he could've had a parasite that infected the other pangasius (i'm assuming theirs multiple considering the way you said it)
2. did you change filters on the tank? if you did, that could explain the cloudiness.
3. how long has the pangasius been in there? alot of times when we introduce a new fish to a tank he or she won't eat for 2-3 days, so it may just be a matter of needing to wait
4. I know this isn't related, but, won't the Oscar and Jack Dempsey eventually kill each other, because they're both very aggressive fish.

This is about your cloudy water: I think when you took out that 12 inch pacu some of the biofilter died off, which is natural. The cloudy water is the bio-bloom of the dying-off bacteria. It will resolve itself in a few days as the biological bacteria adjusts to the new bioload.

The cloudy water isn't a problem. Do some small water changes in the next few days.

I can't advise you on the pangasius without seeing it. He might have a parasite; the white spots might be cysts. How many white spots do you see? Do you see more every day? How big are they? A clear photo would be helpful.

You said the catfish won't eat. Do you mean the pangasius or the pleco?

couldnt get a clear photo, the pangasius is eating now, and i tried raising the heat and putting some salt in to .3 salinity, and left the tank dark so all the bacteria blooms would die, its taken a couple days but its starting to clear up nicely. ill get a pic of the catfish's fins, there are 2 white spots, one on the end of each fin. i think kthey are just attck marks from when he was first put in the tank, they should heal up soon.

From what you wrote are the white spots on the tips of the fins?

yes they are on the very ends of the fins. cant get a clear picture on my shoddy camera lol