Helping to diagnose sick fish?

I have no idea what's wrong with it but I took it out of my main tank and put it in a temporary tank till I fully set up my quarantine tank

 

I can't tell from that photo what may being going on.

How is the fish acting abnormally? What are the physical symptoms?

 

Yea the fish hasn't been swimming around the way it used to and it's losing its color, and the belly of the fish has been turning almost white

 

Hmm... That does not make anything particular come to mind except maybe parasites? Have you tried treating with Prazipro?

What size is your tank? What is the ammonia reading? Nitrate reading? What are you feeding? Do you have a skimmer? What is your water change schedule? What other occupants are in the tank?

 

I haven't treated anything yet because my quarantine tank is still in the process of being setup but my skimmer comes next week finally and all my levels have been good and at zero except nitrates which have been about .10ppm The tank is 50 gallons and currently has two clownfish in it. I feed them brine shrimp and changed the water last Sunday and plan to do one tomorrow with water I just mixed earlier today to help reduce nitrates

 

RO/RODI water? If so which? (Yes there's a difference)

 

Unfortunately I don't have my own RO/DI system so I'm stuck with RO water till I get one, but every time I mix my saltwater I treat it with Prime

 

Are the clownfish acting OK?

Brine shrimp are not a good main food. It is essentially junk food for fish... Would you be able to start feeding Mysis shrimp as the main food with brine shrimp occasionally? I soak my food in Selecon too to help with any vitamin/mineral deficiencies a fish may be dealing with.

 

Yes the clown fish are acting fine and swimming around all day. Thank you for the food tip, I did not know brine shrimp was not a good food I will be getting mysis shrimp asap and start feeding that to the fish