Dropsy/tumor/SBD?

Jan 15, 2013
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#1
Hi,
A few days ago, my betta fish Comet passed away due to a huge lump in his side. All my water quality parameters were ideal. He lived in a 2.5 gallon aquarium with a filter and heater. I was feeding him a little too much freeze-dried treats and I suspected constipation when he started bloating, so I administered the squashed pea and fasting treatment. When that didn't work, I tried Epsom Salts (1/2 tsp. per gallon). No change. I tried Melafix for 3 weeks and as a last resort started a course of Maracyn II, only to find that he had passed on the morning of the fifth day.
His scales weren't pineconing and he didn't have any popeye, so I don't suspect dropsy. The scales, however, were hugely stretched (about 7 times normal size) and his middle looked like a balloon. He was acting, eating, and swimming normally--even had a little bubble nest.
I am going to PetSmart to pick up my new betta today. Can you help me figure out what this was so I can ensure my new fish doesn't get it?
Thanks for your help!
-PetCrazyy919