It's about that size, and looks like the last pic of your boy. It doesn't look as rounded and as uniformed as the way it does in your second pic. Sawyer's does look.. to me... like it's coming from under the scales. I think I could even see some scales sticking up around it as if they were forced away from the growth.
Just took another look, and the fuzzy parts look kinda flakey. Whatever it is, it hasn't affected him in any other way so far. He acts normal. I plan to move him into the new tank tonight.
Thank you :) he's currently in his monthly week long aquarium salt treatment.
If it is Lymphocystis then it's very much so survivable so long as it doesn't get huge and give him any problems moving or eating. I really don't recall if it's contagious but I gave Castiel his own net, for just in case. He's got his own net apart from everyone else's and my 'sick fish' net, i don't think it's necessary to take that far of a level of precaution but, i'm paranoid i guess lol.
I would put him in a qt with aquarium salt (1tsp per gallon) and do daily water changes. If it looks fuzzy then there may be some columnaris growing on it. When I first bought Castiel he had columnaris growing near it and on acouple other parts of his body. I did the aqs treatment first for a week then treated him with API fungus cure. You could probably use API T.C. Tetracycline instead, I don't have any history with that product though.
This Fungus Cure will turn your water green though, so you know. I added part of a packet, just sprinkled a little in, and did this every other day for a week and then gave him fresh water. His fuzziness was gone but i did 5 days of aqs after to make sure.
During this time part of his Lymph had crumbled off, but not a whole lot. When I took him out and changed his water again after all of this even more of it came off, but it like, disintegrated onto the net. Again, not all of it but quite a bit this time.
Now every month I do 1 week of aqs treatment to help keep it from getting any bigger and so far it's worked out quite well.
I'm just worried that it's not lymphocystis and it's something else that I don't know about. I'm looked up lympho on here and have seen a lot of pics of bettas with spots very similar to Sawyer's. Some look like your Castiel (rounded and hard) and some look flaky/fuzzy like Sawyer's. All the comments say to just google lympho to see if it looks the same. They never offer any fungus name or anything. I don't have any fungus meds right now anyways.
So this qt tank I have (I believe you recommended it?) it is 1.5 gallons with the undergravel filter/airstone thing. Do I need that right now? Should I start him with aq salt tonight? How do I acclimate him from his cup to the medicated tank?
That's okay if you don't have any medication right now. It's usually best to start off with AQS and go from there. You can go ahead and start tonight, i don't think there's much of a reason not to. You won't need the under gravel filter or the air stone since there won't be any gravel to be added & you'll be doing daily water changes.
Rinse the tank out and add lukewarm water, add 1 teaspoon of aquarium salt (almost said sugar lol) and let the salt dissolve & add your water conditioner. Let the water cool down to room temperature, it may take awhile. You can use cooler water if you wish, the warm water is just so the salt dissolves nicely.
If Sawyer is in his cup and not sitting in another tank you won't need to worry about acclimating him since the water temperature should be close to the same. You can either pour some of his water out of his cup (down the drain, just make sure you don't dump him out too) and lower the side of the cup into his QT and let him swim out or you can net him and place him into his tank. I do both ways. If you use a net then go rinse it off with hot tap water & it should be fine.
Make sure you place some kind of little plant (silk or soft plastic preferably) in the tank so that he doesn't get too stressed out or anything and feel exposed.
Okay, I have the water in a jug with the salt dissolving. The tank is in place and ready for the water. Sawyer is currently floating in the 10 gallon, but I was worried about acclimating him to the salt water. Do I need to?
Well I decided not to start his treatment last night as I didn't have time to do it carefully and keep and eye on him for a little while. I felt safer waiting until today. So the salt water sat over night (conditioned) in a jug. Is it still alright to use? The tank he is floating in is not currently heated, and is room temperature (between 76-80). So I can just put him in? Also, the tank hold 1.5 gallons, but I should only do 1 gallon right?
1.5 is totally fine, we like using 1 gallon as a base, a little over won't hurt. It's mainly so that it's easier on the owner to change the water every day & because the recipe is 1tsp per every 1 US gallon.
The water is totally safe to use, the main reason you want to change it daily is so the water stays clean, no ammonia or poo or anything like that.
Fill the tank up but leave about an inch or two from the top of the tank, as you would in any other tank.