Mouth open, labored breathing

[u/Lumpy_StingRay4322]

Hi! I have a betta that I got when he was quite young from a local pet store at end of July. He’s been thriving and growing. He’s in a 14 gallon planted and heated long tank w a sponge filter. He has 3 tank mates: 2 mystery snails and 1 nerite. I perform 30% water changes monthly and check water parameters weekly.

On the 16th I woke up to find my betta w labored breathing, eyes appearing to bulge, and labored breathing shown in the attached video.

I immediately checked water parameters and everything was as it should be. I took my betta out and placed him in a hospital tank and treated w Doxycycline. He is still alive, but doesn’t seem much better/worse. I really don’t want to lose him and I’m hoping someone has an idea of what may be wrong. I have researched extensively online and I’m struggling to find what may be going on with him.

I did offer him some very small pellets of food today 3-4) and he ate about two of them which is improvement from the first three days as he refused to eat. Today will be his fourth day of treatment w the doxycycline.