catfish is sick

Question
I have a 52 gallon tropical tank set up in 2003 and it has been doing well. At the moment i have one pearl gourami, 1 small silver shark ,1 angel fish , 2 catfish and 1 tiger barb. my cat fish was doing fine aweek ago but suddenly 2 days back he has been rather weird. he is alive but not swimming like he should be. he was very active earlier. he is now lying down on the sand . his eyes are open , he swims as if he wants to change his place or position.the tank was cleaned last week and the water is fine as it was earlier. the filter has also been cleaned , the temperature is 26 degrees.if possible please do help.  

Answer
Hi lakshmi;

Poor guy. I really don't know what could be wrong if he doesn't have any outward signs of illness. Sometimes fish have organ failure or internal problems that we can't see.

Does he have any spots or signs of injury?
Does he look thin or bloated?
Are there any color changes?

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Chris Robbins

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