may be just wait a little, he need to get use to it the new environment.
If he is healthy, he would be ok, and will chase other (smaller gt's) at no time.
If he sick, then it's another story,but we'll need a symptoms. Does he scratch against hard objects, does he eat?

closed fins and very thin..bad sign..must be infected by parasites or something..usually fishes i saw like this died within days

its swimming around more now and eating. they were feeding it live guppies at the shop i bought it from. it seems to have white spots all over it.yes he does scratch against the rocks. is that bad? cause the other fish are doing it too.

Bad Sign. Sounds like you have ick. Take out your carbon and treat your immediately. If this goes on too long your fish can get internal parasites as well.

Sorry, that was treat your tank immediately.

the fish was like that when i brought it home should i take it out my other fish dont have spots or anything

Since you stated that the other fish are starting to scratch against the rocks, I would treat the whole tank. If you have any invertebrates (catfish, botias, etc.) cut the dose in half.

Slowly raise the temp to around 88 to 90 deg. If it is ick this temp will kill it, but you have to maintain this temp for around ten days. Just make shure that you raise the temp slowly over a couple of days. This should prevent you from needing medication. Ick cannot survive over 85 degrees. Good luck with that it worked for me.

they sold it to you like that? not a very good lfs. a better run one would've quaratined the tank and made sure it was treated before selling it.

Turning the temp up worsks every time as stated earlier by chris..
Ick is usually caused by fluctuations in temperature so make sure yuo monitor you water temp closeley and ensure your heater is working well..

The problem I see with the temperature solution is if the tank is at 76-78 degrees. You want to raise the temperature slow, so your talkin' about three to four days to get the temp high enough to combat ick. If the GT is highly infected, it will be dead by then. Sometimes the temp technique works and other times it's better to use other methods.

Quick Cure is good and inexpensive.You can get it at Wal-Mart&most lfs

thanks to everyone on your input!! Me and the GT appreciate it. I went back to the store where I bought it and told them about the fish they said they could give me the stuff to treat teh tank at a 20% discount. When I pointed out all their other fish(in frontof other customers) with the same thing they gave it to me for free. I will remember not to get anymore fish from there. will post update when all better. Thanks again

YW. Hope everything works out for the best. I noticed at my LFS that all the tanks are supplied with the same water. I asked what happens when bacteria is introduced to his supply. He gave me some BS answer but in the end he admitted that all of his tanks would be affected. My LFS is treating all of his tanks right now too.

*Michelle FYI for the future, since you already probably start treat your fish with medication don't stop and keep going. But for the future:
If your fish have an ick (thats what your fish have now), don't rush to buy medication, specially if the tank is new and not cycle. Med will kill the good nitrifying bacteria and ammonia spike happen, ammonia destroy fish very quickly, unless you going to do allot of maintenance to get tank back to cycle.
The best and harmless way for the small weak fish to treat is to add aquarium salt (1 table spoon per 5 gallon) and raise the temp slowly up to 82 F (you don't need to wait for the temp to rise fully), you can start treatment right away.
Good luck with your fish.

thanks alex. i had salt in already. none of the other fish had the ick just the one that was like that when i bought it. i think it also has the clamp fin fungus. should i treat the tank for fungus too?? or still just raise the temp?

what alex said will kill fungus too