My betta has stopped eating

Question
We have had our betta for 3 1/2 years. Normally he is a very friendly fish, comes when you call his name, comes to the top for food readily, swims around. He has always been a bit lazy but recently he is more like lethargic. He has stopped eating and remains hidden in his house. When I removed the house, he just lays at the bottom of the bowl, completely unresponsive to our voices. He color has slowly been changing from a bright blue to now a more brownish blue around his face. His belly also seems to have a bulge. He has had that for a while now. What can I do? We feel lucky he has lived this long, but this seems to be such a slow and painful process (and very much the same for my daughter who has taken care of him for these 3 1/2 years. We do live in the north east, although we are having the most mild winter I can ever remember. Is there anything I can do? How can I check the temp of his water? Can I use a regular thermometer?

Answer
Hello Sheri-

A regular thermometer should work fine for checking his water - I have a feeling it may be a little cool (explaining the color change and the listlessness.)

However, the bulge may be the most serious thing you've mentioned - as bettas (and all fish, really) age, they become prone to DNA damage, which causes tumors. Some tumors are benign, and bettas will scratch the lump off after a while. Others, however, seem to drain the life from the fish and are eventually lethal.

I would try warming up his water to about 80 F (if it's not that warm already) and adding some aquarium salt to the tank. These will hopefully stimulate his appetite and metabolism - you will hopefully see some improvement.

Good luck with your little guy - sorry I can't offer more.
-Amber Worman