Oscar - lethargic behavior

Question
Oscar was in a 30 gal tank for 1 1/2 years with a plecosamus. Moved one week ago to a 55 gal tank. He was eating well and active on Friday. We were gone two days. Tried feeding them last night - both fish seem lethargic. the Oscar would not eat any of his food. Also he has a "tick" sometimes minor, sometimes involving most of his body. Still seems lethargic this morning. Will take in before and after water samples today (before and after a 25% water change). We also notice he has a one lengthwise area on his tail where the fin was injured. Last night it was a transparent area on his tail looked like it had been injured. This moring it has all come off so he has an 1/4 inch by one inch "nick" out of his tail.
We have an undergravel filter with a powerhead and an external filter that runs the water through charcoal filters.
Could his tail have been injured by getting sucked against the filter?

Answer
Hi Brad;

The tank is very new so it undoubtedly has a high level of ammonia in it from "New Tank Syndrome". Ammonia burns the skin, eyes, fins and gills. His twitching, or "tick" is a reaction to that. Make a 25% water change every day for the next 3 or 4 days to give him relief. Keep monitoring the ammonia levels and test the nitrites too. They will be rising in a week or so. Aquarium salt greatly helps the fish tolerate nitrite poisoning so get some from the fish store. Add 1/2 to 1 teaspoon per gallon of tank water once you start to see nitrites rise. It would be very helpful and much easier for you if you had your own test kits. The tests will also be more accurate. If the water has been sitting in a container for a while the test may not read properly. Here is a link to my article on new tanks to help you know more about what's going on in there;

http://www.xanga.com/Expert_Fish_Help

He may have caught his tail on something from trying to "rub off" the irritating effects of the ammonia. You can use a product called Melafix, available a most fish stores, to help soothe the irritation and help heal the injury.

At Your Service;
Chris Robbins