CichlidFish.com - Fish That Think.

I did a water 3/4 ths water change a few days ago and since then my tiger oscar has hanging at the bottom aroung the air bubbles, he's not eating his usual and not moving around like normal. What should I trouble shoot for?   

NOW let me see if I have this right.. YOU did a 3/4 water change of your tank?? That is like 75% if I am thinking this is what you mean.. WAY TO MUCH WATER OUT/IN!!  YOU have crashed your bio in the tank and now it is having to re-establish its self.. This wil take a few days to do so the Oscar is going to not do to good til then..

MONITOR your ammonia and NITRITES for a good week and see if they spike any.. ANY READING WHAT EVER, DO 20% OF YOUR TANK SIZE VOLUME..

Did you clean the filter too at the same time?? This if YOU DID NOT, will save you on a cycle on your tanks AGAIN... IF you cleanned the filter too, then the tank wil have to cyle AGAIN as YOU distroyed the good bio in the tank... IF you are lucky, just the NITRITES SHOULD SHOW A READING.. IF not then the Ammonnia is going to show first, then the nitrites.. YOUR FISH ARE IN DANGER of both so monitor them daily until they fall.. and do the 20% water changes every other day until they come down...

FEED EVERY OTHER DAY UNTIL THEY DO GO TO 0ppm...

YOUR Oscar wil not eat as you have upset the tank bio, don't worry, he wont' starve... take out all foods that he does not eat and try again tomorrow...

Yes I did change the filter also. I took out so much water because I was over seas for 8 months and it was only cleaned maybe twice while I was away. The water was really clear when I got back but I just couldn't look at the filth all over the tank, filter, light hood, and plants. I know that I may have over did it, but now I can stand to look at it. I'll have the water checked first thing in the morning.  Again thank you....

YOU did not say that when you posted that the tank had been neglected.. I understand WHY you did what you did..
I would have done the same..

WELCOME home!! And I am sure the tank should be fine.. just watch your Ammonia AND NITRITE for a good week and see if either one has a reading.. Keep ME/US posted on what you discover on the tests..