One sick fish

I have a sick betta. I got him about a week ago, I was at work (I work at a pet store in the fish dept) and a lady brought him in. She basically said that she didn't want him any more, and could we take him. We said yes, and when we took a look at him, we couldn't believe it... you could SMELL the ammonia in the water. His fins are all mangled, but they aren't fungus-y or rotting... he was a little bloated too. I took him home. He's actually a very pretty marble CT, I remember when we sold him.

I put him in a 1-gallon bowl with some melafix (just a few drops) and some java moss. He didn't eat that night, which is normal for a stressed fish. I tried the next day, and the next... unfortunately, he hasn't eaten at all. I've tried peas, pellets, freeze dried bloodworms, frozen bloodworms, and frozen brine shrimp. He won't even look at food. Also, I noticed a few days ago that a lump was forming on his side, and it appears to have ruptured in the past 24 hours.

Pics of the lump are attached. From the top view, the thing that looks like it's protruding from the lump is just his ventral fin.

He's not pineconing, his fins aren't clamped, no popeye, fungus, ich, velvet, anchorworms... he's just very listless, won't eat, and has this wound.

Water is conditioned with Aqua Plus, bowl water has been changed 100% every 3 days.

Right now he is in water that is treated with erythromycin (spelling?). Any ideas?

Thanks.

Here's one from the side view.

MelaFix® is a good choice. It'll help the skin tissue to heal.

Erythromycin is effective against a wide range of bacterial infections. Do complete the course of the medication as instructed and keep the water clean.

Not sure about the side-effects of Erythromycin in fish. It sometimes causes abdominal discomfort, nausea and vomiting in humans.

Try feeding a live brine shrimp (artemia). Hope your betta will get better. Do update us on its progress.

Oh,how cruel for the betta,its so beautiful too.I saw one with the same color at Petland not too long ago.

Thanks for your advice. I will try what you suggested. Hopefully he'll make it through, I just wish I could get him to eat!

Unfortunately, he died this morning. Thanks, D Chia, for your help.

Aww I'm so sorry to hear he didn't make it

RIP poor little guy. It's sad that some people will buy fish just for decoration, and then when they get ill because the owner hasn't looked after them properly they want to get rid of them. If they don't know how to look after an animal - DON'T BUY THEM! It makes me so upset and angry to see that sort of thing happen. I'm sorry that you lost him, but I think you did great in caring for him. At least you tried your best.