betta w/ lump on side of body...help!

Question
Hello-
I've had my Betta for a year and a half.  I bought (rescued) him from a PetCo.  He's been very, very happy in his 1/2 gallon tank (I treat the water with Doc Wellfish's Aquarium Salt, Splendid Betta Complete Water Conditioner, and Aquari-Sol).  I know it's a 'he' because he used to blow bubble nests at the top of the water.

About two weeks ago, however, I noticed a lump growing on his left side.  It's gotten bigger but has now stopped growing -- there seems to be a white "head" at the roundest part (sort of like a pimple) ..he swims around much less, still eats a fair amt (but not as much as normal), but he lies sort of sideways on the bottom or the top of the water, and rests on the (fake) plants in the tank.  

I'm not sure what to do -- I haven't fed him as much, in case it was constipation.  I don't think that's it.  Is it a tumor?  Dropsy?  Should I try feeding him small amts of the inside of peas?  Is there any medication I can try?

Any help is very much appreciated!  I love this little guy.

Thanks so much.

Answer
Hi K;

He may have an abcess or something. You could try using some "Maracyn Two". It's an antibiotic that absorbs inside the fish to get where infection is.

He seems to also be having trouble with his swim bladder. It's really hard to say whether they are related. Here is info about swim bladder problems;

http://groups.msn.com/TheBettaObsession/illnessamptreatmentpart2.msnw

I hope he feels better soon.....

At Your Service;
Chris Robbins