What could have caused this?

[rbaby]

I have 2 percs...1 is so incredibly healthy, his color is vibrant and he's not fat...but he's certainly healthy.
The other however...I don't know what happened. I don't know what could have caused this. He was eating healthily and had a healthy appetite. He started to get thinner...and so I changed their diet from Brine Shrimp (I know I know...I didn't know any better ) to Mysis Shrimp.
He's continued to dwindle down...even though he would still eat. He's now skin and bones and is basically on his death bed. I'm really sad and I really hope that I could help him but I don't know what to do. He's really really thin and I checked on him this morning and now he's basically all white, I don't think he will last through the day.
I placed him in a quarantine tank and put in some additives in the water...vitamins and stuff. I also spot fed him and tried to get him through it but to no avail.
My other perc and goby are doing fine, so I'm pretty sure that he didn't starve to death. I don't understand what could have happened? He had no visible ich or any kind of disease...
I would feel terrible if all this was my fault...my family keeps saying he was just sick...because all my other fish are doing great. What could have caused this? Thank you.

 

[bang guy]

Sounds to me like some type of internal parasite.

 

[rbaby]

Was there anything that I could have done? What are the chances that my other fish now have this parasite? Thanks Bang...I feel a little better knowing that I wasn't the cause of his condition.

 

[bang guy]

I can't think of anything. Maybe Beth knows of something.

 

[beth]

When you say the fish was all white, did you notice if he was "pealing"? Take a look at the Diseased Fish thread and check out the pics there of clowns with brooklynella. Did it look anything like that? Did you notice rapid heavy breathing? How long have you had this fish?
Don't beat yourself up over this. We have all lost fish in this hobby. The important thing is that we do the best we can, and learn from our mistakes and experiences.