oscar fish not eating

Question
QUESTION: I used to be a freak about my water levels and i always used to kill my fish so my friend who has 6 tanks and has had them for quite sometime told me to stop checking them and so i did then i checked on thursday and it was 8.0 i tried to ignore it and i couldnt so i changed the cartridge and put some amquel in now it is wednesday and my ammonia is .50 which is fabulous. but now my oscar is not eating and he used to come to the front of the tank when i used to come over but now he runs away. So my question is could he be moping again from the change in ammonia happened so quickly or is it more likely hes sick.
         thanx in advance
         nikki

ANSWER: Hi Nikki
What size is the tank?
Anything else in the tank with the oscar?
How often do you usually do water changes, and how much water do you change out each time?
What's the other levels, nitrite and nitrates reading?
And, how large is the oscar?

Christy

---------- FOLLOW-UP ----------

QUESTION: The tank is 29 gallons (i should have a bigger one soon). i have a medium corydora in the tank with him.
i usually dont becuase i used to change water and eveytime i killed my fish so i am always nervous to do it.
they are bad i just tested them to day and realised how bad they are.
nitrite-2.0
nitrate-20
the oscar is a baby about 2 1/2 no more than 3 inches
he has recently started opening his mouth alot and then he freaks out it almost looks like hes have a siezure and then he will try to eat and its almost like he cant get the food or like his mouth wont let him and then he gives up

Answer
Hi Nikki
Hopefully you'll have the larger tank soon.  1 oscar needs at least a 55 gallon tank, though 75 gallons is better and easier to maintain with them.  I don't what problems you had before with the fish dying after you changed the water.  Without further info, all I can think of is you didn't use a dechlorinator(I"m sure you did though lol), or if you didn't do them frequent enough, and then only did one large water change, that can actually kill them as well by sending them into shock-ph shock, temperature shock, etc.  Your best bet for a normal stocked tank, weekly water changes of 25% along with a weekly gravel vacuum.

However, for your current situation, I would recommend doing daily water changes of at least 20% until you get the ammonia and nitrites at 0 ppm-which is the only acceptable level.  Nitrates you want to aim to keep them under 20 ppm. Then, until you get the larger tank, I'd do them every 2-3 days.  Not sure how long the tank has been set up for, if it's going through the cycle process(which it does sound like), or if the water quality is poor due to lack of water changes.

When you do get your new tank set up, be sure to run the filter on your current tank along with the new filter.  Whatever beneficial bacteria that's in the old filter will help kickstart the bacteria growing in the new tank, hopefully minimizing the cycle process of that tank as well.  

Try the daily water changes and see if he starts improving.  If not, let me know and we'll take it from there.  Frequent water changes are a must for all tanks, if you take of the water the fish will take care of itself really.

Good luck!

Christy