Cloudy eyes

Question
Hello Lynda,
  My husband and I have an Oscar, and we're not sure how old he is, but yesterday we took him out of the tank to clean it out thoroughly.  After we did this, we put him in a cooler with water and his heater and filter.

After the tank was cleaned (no chemicals, just with water) we put him back into his tank. He was completely a different color when we put him back in for atleast 4 hours. He is normally purple, but the purple changed to a greenish olive color. He wouldn't move around his tank for the rest of the day, and wouldn't eat.

The next morning he was back to his normal self, but I noticed that he has a film over both of his eyes. I am very concerned about this, and I don't really know what to do to get it off of them.  Any help of information would be greatly appreciated.  Should I be concerned about this, and try to remove it somehow?

Thank you,
Tiffany

Answer
Hello,
This change must have stressed your Oscar.  Did you keep your old sponge?  If you changed all the water, and filter material, this is not good.  The sponge can last for a very very long time, it is full of good bacteria, and when you rinse it, you should always rinse it in the same water temperature as is in your tank.  Changing all the water is very bad for fish, and I would think that this is the problem.  How big is his tank?  An Oscar need at least 60 + size tank.
Never change the water completely as the fish needs the good bacteria that is in it.  Weekly water changes are important, and if you do this, you do not need to change all the water.  The water chemistry is now changed, and I doubt that there is good bacteria in it.  Check your water for ammonia, and nitrates, and if there is ammonia in it, or nitrates, go to the Pet Store and buy an old used sponge.  Put it in your filter, and the next day check your water again....do water changes until the ammonia is down to zero, and the nitrates safe.  
If the situation gets worse, you will have to treat with Malafix, but you cannot do that now.  You must wait till your water is safe, and maybe his condition will clear up by itself hopefully.
I also want to add that diet is very important to Oscars.  Vary his diet..do not feed him feeder fish as they are mostly full of disease, and if eaten by the Oscar, he too will become sick.  Feeder fish have no nutritional value, and should not be fed to fish.
Hope this helps
Lynda

I'm sorry you did not understand fully my answer, so I will make it more clear to you.  You never, ever change all the water in a tank.  The reason for this is that there is good bacteria in an established tank.  You could remove 50% of the water if your water is in bad condition...and remove 25% the next day, and so on until your water has no ammonia, and nitrates are safe.  Ammonia, and Nitrates kits can be bought at the Pet Store, and they should be number one in your fish cabinet.  You must check your water weekly, and make water changes weekly.  My concern is for the fish, as I love them, and do my best to help people understand.  Your oscar had a reaction to this change of water.  You cannot treat him if your water isn't safe...this is why you must check your water first before putting any medication in it.  Once your water is free from ammonia, and nitrates are safe, then you could treat if you see that your Oscar isn't getting any better.  Putting him in all new water resulted in making him sick.  Chances are that he might get better on his own, and medication is the last resort.
Hope that this is more clear to you, and that your Oscar will get better.  I know how attached we are to them, as I have two in a 150 gallon tank, and love them to pieces.
Lynda