im really new to the whole fish-keeping business.

i got a blue/purple siamese fighting fish as a gift from my fish-savy friend a week ago. he started out in a half gallon glass bowl, and three days later i bought a 3 gallon plastic hexagon tank with the light and everything. he seemed fine, even with my 3 cats staring at him (i keep the tank on my floor). a few days later he began losing color and now burries his head under the rocks. up until today he was eating just fine, but hasn't accepted any flakes that ive given him today. i keep the filter/air pump thing off, and i am going to be getting something to put in the water for stress. otherwise i don't understand why he has been behaving so strangly. im afriad that he isn't really gonna make it for very much longer.

some advice or some help would be greatly appreciated