Is This Lymphocystis?

The dragon scales seem more prone to this in my experience. Well done on doing the best you can for him, which is all we can all ever do.

I've also read that sometimes it can go away on its own, but I won't get my hopes up. Here he is in his tank (not sure why the picture is so washed out - it looks better in person). My 5 year old daughter picked out the fluffy red decoration. Betta seems to like it actually, even if it is a little brighter than I might have chosen. He likes to swim through it, sometimes stopping and resting right in the middle. I'm thinking he'll like the banana plant leaves once they get large enough for him to rest on. He is very observant. He patrols the tank inspecting everything, eating the occasional tiny snail and attacking the larger ones. If they are small enough, he is actually eating the snails, shell and all.

I read that it can be caused by stress and so by giving him a good life in a nice tank should lower any stress levels and you never know - he might bounce back

I will update this post as time goes on, in case it might help anyone else in the future.

Two photos below show Cannonball's progress. One is in mid April when it was looking so much better. The lump seemed to shrink, not fall off, but the edges of the area stayed a bit raised.

The other photo is today, 26 days later. As you can see from the photo, the lump has returned, larger than before. It is also darker than it was. He also has a small white lump on his head. In the photo, it just shows up as a blur on his face, but it is a small lump like the other. It obviously has the potential to become really bad, especially considering the location.

I am keeping an eye on him and his quality of life (as best as I can understand a fishes' quality of life). He still swims around inspecting everything and eats his food and the snails that are small enough. Although, I have noticed the past couple of days that he hides a little more than usual.

In the previous photo, the dark color makes the lump look like a hole, but it is indeed a lump. I think the convex quality can be seen better in this photo, even though it is less well focused.

The second photo is of his little bubble nest that he built under a lily pad from the banana plant. I wanted to post it here just to insert a bit of happy, showing that his life is still carrying on as usual so far.

I'm so sorry to hear that. I do know how you feel
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The lump on my betta did sort of deflate every so often, then regrow even bigger than before. But the fish acted quite normally until the lump got so big it was invading his gill.
 
 
That new spot does look worryingly near your betta's gill and eye. All you can do is monitor the lumps until you think the fish is suffering too much. His behaviour will tell you.

So, poor Mr. Cannonball now has fin rot that I have been unable to cure. His water is very clean, no ammonia, nitrites, or nitrates. The pH is still in the 6.5 - 6.8 range. I do water changes twice a week although the tank is filtered and fully cycled. I have scoured the internet for treatments and I have tried aquarium salt, artemiss, and the extra water changes but it still isn't better. Everything says fin rot is either from poor water or a weakened immune system. Because I know his water is good, I think the cyst is compromising his immune system. Since this is proving to be treatment resistant, I am worried that this is hurting him. By "this"I mean the fin rot but actually I'm worried the cyst is hurting him as well. He has been hiding more lately. I am not sure what else to do. I am open to suggestions if anyone has any.

Another update: The lump grew and shrank again and is starting to re-swell. I am continuing to be diligent about water changes and making sure that his water quality remains excellent. His fin rot is not getting any better unfortunately. Also, most upsetting of all, his eyes are becoming covered with scales. I read that this is not uncommon for dragonscales. Why are these poor animals bred when such terrible issues are known?
 
Poor fella has been staying at the bottom of his tank, which is covered with plants and where he can stay hidden. He comes up when I open the food door on the lid, but because he can barely see now, it takes him much longer to eat. I made a feeding ring from a plastic milk ring (that goes around the cap) but he just bit it and didn't see the food inside. Instead now, I feed him in a patch of floating pennywort that keeps the food from drifting off before he can find it. He comes to the patch of pennywort now when I open the lid.
 
I have noticed him drifting sideways a few times and also laying with his nose in the plants, face down, tail straight up, but then he recovers. This has only happened a few times, but it worries me.

The scales growing over the eyes is indeed common in dragonscales. I had this with another betta, which is why I won't buy dragons now. Mine had one eye completely covered and the other eye partially covered so he could find his food. But I was very careful during water changes and made sure that anything I moved to clean the tank better was put back in exactly the same place.
Does this look like yours?

Not yet. I'll try to get a picture when I get home.
I won't be buying anymore "dragonscales" either. Judging from my research, Cannonball may not even be a "pure" dragonscale, but he obviously has been bred with enough of the negative traits to not make a difference. I intend to write to PetCo to share the experience I've had and that many others have had with this strain. They should understand what they are supporting.

Here are some pictures of Cannonball and his world today. Not sure how well it shows, but his eyes are growing scales over them. He can still see a bit, thankfully. I took a picture of where I feed him now, in a patch of pennywort. He still makes bubble nests under the banana plant lily pads. You can see his tail has deteriorated though.

He had a good day today as far as I could tell. He didn't drift sideways and he found his food quickly.

Poor Cannonball's cyst has grown quite a bit. He looks rough, but we've had him for about 7 months now and he's still alive so we are counting our blessings. Some days he looks livelier than other days, but I still don't think he is suffering. He still does his tours, although less often. There were a few days where I thought it was going to be the end because he was just sitting on the bottom but he seems to have rallied.

I did halt the progression of the fin rot finally. I used Marineland's All-in-One remedy and it worked beautifully. His tail did not heal much but at least it stopped getting worse. I've read that lymphocistis weakens the immune system, so I'm happy with what we were able to acheive.

That looks just like my betta did. His problem was where the big lump was - so close to his gill that as the lump grew it covered the gill. Your betta has been spared that, thank goodness.

I do agree, as long as he's behaviour is normal for a betta, don't do anything. His behaviour will change if he starts to suffer.

I just read thru this entire thread and must commend you and your son for being such caring people and taking such amazing care of his poor little guy that was dealt a tough hand at life. You've given him a wonderful home and much love which makes him very lucky