Betta Tumor

[AllNighter]

My favorite male Betta has recently been acting really off, so since he's mostly transparent anyway I took a flash light to him to see if I could spot anything, just in case. Didn't see anything strange. His white scales suddenly got dark and greyish. He's normally a really active fish, and he's been really slow, hardly moving at all. I have to check on him all the time because I keep seeing him laying on the bottom of his tank. That's how he normally sleeps anyway, or in the middle of his plant, but he's started sleeping on his side. Which is weird. And a lot of times when he's asleep I see him stop breathing for several seconds before waking up. Fish have sleep apnea? He's also having trouble controlling where he's going and how he's floating.
I took a flashlight to him again today, because I noticed he was swollen, and I've found a tumor just in front of his belly. It's pretty big, and looking through my pics of him I can see where it starts becoming visible, about 6 days ago. I'm really torn up, and I've no idea what to do. Can anything be done for a tumor? He's been my baby for over a year now, some of my others lived nearly six years. I've never dealt with anything like this before, and I'm at a total loss as to what I can do for him. He has such a personality, I really don't want to lose him if I can help it. Does anyone have any advice? I just need to know what I can do to help him...

(I have no pics available right now, I can get some later though)

Edit: He's also been biting his fins lately, he's never done that before, so I've no clue if it's related in any way. Nothing in his environment or care has changed to cause stress...

 

[NickAu]

Can you please answer the following questions.

How big is the tank?
Has it got a heater? What is it set to?
Has it got a filter?
How strong is the current?
Is it cycled?
How often do you change water?
How much water do you change?
Do you vacuum the substrate?
What additives or chemicals do you use? Eg De Chlorinator?
Do you use tap or bottled water? If bottled water please give us the brand.
Do you have a water test kit?
Can you tell us the readings for ammonia, nitrite and nitrate?
When you clean the tank can you tell us exactly what you do.
What do you feed him? how much? how often?
Any tank mates? What sort how many?
How long have you had the Betta?
Has he got a history of illness?
Any plants or decorations? Please give details?
Can you provide a close up photo of the fish?
Can you provide a photo of the tank?

 

[AllNighter]

How big is the tank? -3.5 gal.
Has it got a heater? What is it set to? -No, we don't need one where I live. His tank is always about 77 degrees.
Has it got a filter? -No.
How strong is the current? -N/A
Is it cycled? -Yes.
How often do you change water? -Twice weekly.
How much water do you change? -50%
Do you vacuum the substrate? -No
What additives or chemicals do you use? Eg De Chlorinator? -Tetra Aqua Safe
Do you use tap or bottled water? If bottled water please give us the brand. -Tap
Do you have a water test kit? -No, my roommate threw it out on accident and I haven't gotten another.
Can you tell us the readings for ammonia, nitrite and nitrate? -Not the current readings, no.
When you clean the tank can you tell us exactly what you do. -He just has a couple of rocks, so I scrub them with a toothbrush.
Has he got a history of illness? -No. He's been perfect up until now.
Any plants or decorations? Please give details? -Two smooth rocks, one plant. It's an Amazon Sword.
Can you provide a close up photo of the fish? -I can. I'll do so in another post.
Can you provide a photo of the tank? -I can. I'll do so in a second post.

 

[AllNighter]

What do you feed him? how much? how often? -5 pellets every other day
Any tank mates? What sort how many? -One Mystery Snail and Two small Ghost Shrimp
How long have you had the Betta? -A little over 1 year. By about two months?