betta w/ lump on his side...pls 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,

The symptoms you have described sound more like some sort of tumor than dropsy or constipation. A fish with dropsy has a rounded abdomen, which resembles a pinecone when veiwed from above - the scales stick out.

You add aquarium salt to your water which is an excellent preventatve and treatment for most diseases, but in the case of a tumor it may actually cause the fish to retain fluid in the tumor, which we don't want happening.

Stop using the salt, if possible do a 50% water change today and another tomorrow so it is all gone. Then go and see if you can find a good quality broad spectrum fish medication. I have had nothing but success with Wardley's Promethyasul, but see what your fish store has.

Keep your boy's water warm (78-82) and clean, with ongoing weekly 50% water changes, which any size tank needs.

I hope he recovers!