hi every one i have a sick red O his not eating hasent been for ages now at least 2 weeks have been trying to cure him all ph nitrite ammonia are at zero so all thats fine hes got fin damage (not from other oscars looks like a small paricite has done it) as shown is picture.
hes gasping very heavily loosing colour poor guys got the lot plz help

If your PH is 0 then you have done your tests wrong somewhere, please recheck, PH is not as important as ammonia, Nitrite,nitrate,. By the look of your pic you have a few fish in the tank. can you give us tank size, filter in use, how many fish you have and size and post the results of your water test. Ammonia and nitrite should be 0 nitrates between 0 & 40 but below 20% is better. oscars not eating are a common problem and once they start gasping at sureface are not far off dieing. if you check the site there are many post for the same problem. A good pic of the fin may help but I dont think this is your main problem and is only a small part of it.If your fish have parasites or is unwell it will not eat, sick fish is mainly due to poor water conitions. Please get back with more info.

lol sorry bout the ph i keep it at 7.0 ammonia is at 0 nitrate at 0and nitrite at 20.
i had just three oscars in the tank which is 5ft x2ftx2ft with a eel tail and a sleepy cod i took the sleepy cod and eel tail out today because i brought a pair of oscars today at a good price i thought that the oscar could be sick becuse the other 2 that were with him were picking on him so he was getting stresed out so mabey with the 2 new ones he mite settle down a bitith 5 of them in the tank we'll see.
the sick oscar is about 6-7 inches and the tiger is about the same the albino tiger is fully grown at 13 inches hes alot bigger than the two but he was given to me and if i didnt take him the original owners were gunna flush him (this was when he was smaller lol)
but hes a very peacful fish even of a night .
he dosent always gasp at the suface only sometimes hes been really sick for quite a while now

welcome to the site Dean

Now I am hoping that you have got nitrites and nitrates mixed up. You're telling us that nitrate is zero and nitrite is 20. The fact that most test cards do not go up to 20 on nitrite tests makes me think you have got them mixed up.If indeed your nitrites was 20, your fish would be dead by now.

Anyway, could you give us a bit more information on how you clean your tank and filters?

You say he doesn't always gasp, does he eats it when he is not gasping? and none of the other fish are showing these signs at all?

I think I've had the same discussion about fish not eating around three times this week with different people, it does seem very common and is something that is very difficult to fathom out. Obviously if you have done your water tests correctly and the water is in good condition, it does point to the fish being ill which is a different ballgame altogether, fish are notoriously difficult to diagnose, even by professional veterinarians.

I'll be out most of today, be back later on.

Firstly if you have a problem with your fish it is not a good idea to buy more fish until everything is sorted out. If the problem is water quality or contagious you will then have problems with the new fish

You now have 5 oscars in a 125g tank. This is too many and you are overstocked. It is going to be extremely difficult to maintain good water quality with 5 full grown oscar in a 125g. Also your problems will get worse if end up with a breeding pair

Now to your problem, if the fin damage is from a parasite you should be able to signs of them on the injured fish and on the others. It may be fin rot but I suspect the fin damage is from fighting with the other fish. Can you post a pic

Is the top of your tank still or rippled. If its still try putting in an air stone or adjusted the outlet from your filters so that they make the surface ripple. This increases the amount of oxygen in the water

What do you feed your fish. Oscars can get bored of the same food all the time. If you feed only pellets then vary the diet. Try new foods to try to tempt the non eating oscar, maggots, worms, meal worms, defrosted frozen prawns, bloodworm cubes ,any small fish from the fishmonger and any insects you can get.

Do you have a quarantine tank? if so, I guess it would be best for everyone to put the Red Oscar in it. You would be able to monitor his/her health status better and provide propper care (e.g. meds, higher water temp, feeding sparingly).

I would address each issue separetely:
a) Raise levels of dissolved O2 (focusing on water agitation, complement by adding airstones) for the gasping symptoms.
b) Feed sparingly, and remove any uneaten portion that remains there after a few minutes
c) Consider propper medication for the fin problems, including raising a bit the water temperature (to avoid fungus or other opportunistic agents).
d) Keep in check all water parameters, performing frequent (unless not advised for medication) partial water changes.

Hope you are using liquid reagents tests, I wouldn't trust strip test for accuracy.

I do have a pH question, what do you mean by "the pH I keep at 7.0"? Do you tamper with water pH? if so, by which means? Or is that the pH freading rom your water source?

Once your fish gets well, please, consider setting up another tank(s) for the other guys, they won't be able to live in that tank size for long. You could keep a pair in it though.

Pepe
Santo Domingo