a few days ago, i noticed my 4 month old oscar about 5 inches in size had a little bit of its fin missing on the right side. i do a 20 percent water change on my 55 gallon tank on a regular basis, but this raised a concern so i went on with a 50 percent change and gravel vac'd the tank. i changed the filter bags as well. i went out to the pet store and purchased "jungle tabs" for fin rot to cure my fishes fin/flapper. today i have noticed that he is very lethargic and is slowly moving around the tank and this raises concern to me. i have had my water tested and all nitrate and ammonia levels are fne. any ideas ort suggestions?

Hi, and Welcome!

First off, we are going to need your exact readings for Ammonia, Nitite, and Nitrate.
When the Fish store tells you they are fine, they often aren't.

Is there any way you could post a picture of what is going on? My guess would be that it is not fin rot. But a pic would really help!

ill get on this now! give me a minute! thanks!

Make sure you use an image hosting site like Photobucket, then just post the img code here

as far as levels go i do not have anything to measure it with, i went by what petco was telling me. he is in the tank with 2 tinfoil barbs and they havent changed at all

OK, Here is what you need to do... Go back to Petsmart, or Petco, or where ever and buy a Liquid Test kit. API is the brand. You can test for ammonia, nitrite, and Nitrate,and PH.
These reading will tell us a lot.

how big is your filter? how often do you do a water change?

My best advice would be to rehome the tinfoils as they get HUGE. Your tank is only big enough for one oscar.

I would bet your levels are off, and there is some fin nipping going on. When we get your water sorted, your oscars fins will heal nice and quick.

its a double filter designed for the tank, it came as a bundle 55g tank. i do 20 percent water changes every week. i will do as you say and purchase this kit tomorrow. thank you for all your help so far. should i be concerned right now?

OK, that is part of the problem... That filter is designed for tropical, community fish.

You will need to more than double the amount of filtration for just your Oscar... I would look to add a Fluval 405 canister ASAP.

And in the mean time, do a 50% water change at least twice a week.

I would get these things corrected ASAP, and we will quickly help you make your Oscar better and HUGE!!!

Nickisue is spot on. You only have enough room for 1 oscar and tin foils are big fish. Rehome them ASAP. In the meantime do a 50% water change and get a cannister filter. they have ratings on tank size for them, this is for community fish. Oscars are messy fish and require twice the filtration. So go for one rated for a 110g tank. As Nickisue say a fluval 405 will be perfect