Hey everyone, I have been a betta keeper for many years and I pride myself to think that I'm an expert on them (Hope my joke goes well with y'all). Of course I'm not an expert, and I'm always learning new things. However, I do know quite a bit about these beautiful fish and their illnesses. But the betta I have now has me stumped. Starting about 4 days ago my betta slowly lost his appetite. Well, he would come up and nip at the food acting like he was starving, but he wouldn't open his mouth and actually consume the food. It is really weird. It's like his jaw has clamped shut and can not open. Yesterday, he only surfaced for air and a look at the food once that I saw, but otherwise he just laid at the bottom of the tank. Today, he hasn't hardly moved from his little cave. I did a water change because the tank needed a cleaning (I was putting it off, not really wanting to stress him out). He seems a little better with the water change, his orange color has come back a little, but he still hasn't moved. There is a lump below his jaw, where both his gill covers meet on his throat. I've noticed it grow a smallest bit bigger yesterday and now today. It's so strange and I don't know what to do. He lives in a 10 gallon tank, heater temperature automatically set to 78 F, filter, light off most of the time (not wanting to stress him more), Ammonia 0, Nitrite 0, Nitrate around 7. I don't know why he's ill all of a sudden and why it came upon him so quickly. Image by adh/smile posted Jun 24, 2018 at 1:29 PM Image by adh/smile posted Jun 24, 2018 at 1:31 PM Image by adh/smile posted Jun 24, 2018 at 1:30 PM NOTE: He is a crown tail betta and his fins are naturally that ragged. He is not suffering from fin rot or anything like that. His fins are fine.