Columbian Shark / Black Fin Shark Not Doing Well !help!

[Pleco93]

I have 3 of these fish in a tank and this morning one of them wasn't swimming and was just floating around with the current of the tank. I dropped some food in and he was able to get it, but it seemed to take a lot of effort. After eating he stopped swimming and layed on the bottom of the tank for awhile. He seems to only be able to swim in short bursts. He also appears to be bloated and have some fuzzy stuff on his fins. Below are some pictures. I have tested the water and all levels are good. 
 
 
Does anyone have any idea what this could be?
 
 
 
 

 

[Byron]

My disease experience is extremely limited so I am not going to start guessing.  But as I saw this new thread, I thought I would suggest you provide more data which others with the experience will end up asking for anyway.  Starting with the tank size, fish species and numbers; water change info; any additives/substances being used; how long have you had this fish; any new fish recently added to the tank, or any other changes.
 
As for water tests, please give the numbers.  What may seem "good" may indicate something to another aquarist more experienced in disease.  Tests for ammonia and nitrite should be done at the first sign of trouble, then nitrate and pH.  Also, what is the GH.  And temperature.
 
Byron.

 

[RobRocksFishTank]

My bet is inappropriate parameters, most likely pH is too low. But it's only a guess.