BIG lump on Betta

Question
Our betta is about 1 year old. He has a lump about half-way down his body, a little bit past the start of his anal fin. When you are looking at him head-on, the lump on in his left side, and it looks like someone literally stuck a pea under his skin. It has been getting progressively larger over the past week or two until now the skin is stretched so tightly it is white-ish in color.

We have tried the standard treatment for constipation --- not feeding for several days, then feeding a pea --- but none of that has helped, and we've tried changing his diet as well.

He appears perfectly healthy otherwise. He is swimming just fine, has a good appetite, and is making some big bubble-nests. Currently we are treating him with Maracyn-Two in case it is an internal infection, but it is near the end of the 5 day cycle and there is no change.

DO you have any thoughts on what this might be, and what I should do next for treatment?

Thanks.

Answer
Hi Dan, I'm sorry I couldn't have gotten to you sooner.

Sounds like either a cyst or a tumor. It is very difficult to know since it could even be bacterial in nature.

You are doing an excellent job with the maracyn-two treatment as that's what I'd recommend. Some people might suggest feeding him a "gel-tek" food that is antibacterial in nature. But many fish don't accept this and it may not do any good either.

If its a tumor of course there is nothing you can. Fish often behave perfectly fine even with very big tumors and cysts. I currently have a foot long oscar with a tumor on his side similar to your betta and he has lived with it for almost a whole year now. I haven't got the heart to put him down yet because he  still eagerly eats and swims around like a normal oscar in all terms.

The best I can recommend is continue giving him the good care you have been giving him and if you want to, you can try with the medicated foods and see what happens. But I can't guarantee anything unfortunately :(

I hope all goes well!
Karen~