Originally Posted by Silverfang
my thought is a tumor. My boy is developing something similar. I wish I had better advice. Swim bladder is located closer to the base of the tail (well the caudul penduncle... no idea if that is spelled right).
Please, if you could fill out the sticky located here http://www.bettafish.com/showthread.php?t=49233
we might have a better idea and can offer better advice.
What size is your tank? 5 Gallon
What temperature is your tank? N/A
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? The filter has a type of aeration built in.
Is your tank heated? No
What tank mates does your betta fish live with? None.
What type of food do you feed your betta fish? Top Fin Color Enhancing Food Pellets
How often do you feed your betta fish? Every other day.
How often do you perform a water change? Only when necessary.
What percentage of the water do you change when you perform a water change? 3/4
What type of additives do you add to the water when you perform a water change? A regular all-in-one water conditioner.
Have you tested your water? If so, what are the following parameters?
Hardness: 75 - soft
Alkalinity: 80 - moderate
Symptoms and Treatment
How has your betta fish's appearance changed? Has a lump on left side.
How has your betta fish's behavior changed? He's still pretty active.
When did you start noticing the symptoms? A week ago.
Have you started treating your fish? If so, how? I did warm water changes, but that's it.
Does your fish have any history of being ill? No
How old is your fish (approximately)? About a year.