Lethargic betta

Hello everyone! Recently, my betta has been very lethargic, he sleeps most of the day and only comes up to get air a few times a day. When he does come up i try to feed him but he just tries one pellet, spits it out and thr goes back down. He has always been pretty sickly: when i got him he had really bad fin rot, extremely close to his body. a few days after i got him and started treating him he got ich, and by treating that, the progress i had made w his fin rot was gone. I then treated him again for fin rot, and he seemed alright,aside from the fact that he would he would get a slight fin rot if i was even a day late with his water change, but his fins would regrow the day after the water change. Besides that, he had an episode when he would get rly bloated after eating and would float at the top, as if he had swin bladder disease, so i started feeding him less and he was better. (and a few weeks after he got better, i started feeding him normaly and we havent had issues since then).throughout this whole ordeal, he has never stopped eating; in fact he was always hungry 24/7, which makes the recent development even more worrying.

For context, I've had him for about a year and a half, i keep him together with a Nerite snail, and i had him in a 5 gallon tank with a heater and a filter until a few days ago, when i moved him to a 9 gallon one. The water temp used to be at 23°C (i had set the heater to 25 but eithout my knowledge it only heated the water till 23°C, so i set it to 27°C and now it heats till 25°C. i changed the temp when i was moving him from one tank to the other, and i let him adjust to the water temp in a container with water from his original aquarium for about two hours and gradually added water from the new tank etc.).

And so, my question is what i should do now and if i should move him to a quarantine tank or not? I've attached some pictures of him and the tank too.

He isnt looking good at all... How long has the tank been set up for? What are the water parameters using a liquid test kit like API? @Colin_T knows treatments and may be able to help...

He looks like he's struggling. Did you cycle the new tank? I agree you need to check the water for ammonia, nitrite, and nitrate. Not sure what else could be problem.

My betta got sick and looked just like that... I would try some API BettaFix and some Aquarium salt. There are so many televet sites. I would get him an appointment ASAP.

Hi. I'm so sorry your baby is having issues! If I were you, I'd move him to the quarantine tank, and try a dose of kanaplex. If not kanaplex, maybe some epsom salt, because he seems bloated. Together with the salt OR the kanaplex (dont treat him with those 2 the same time), you can put an ial in the qt tank, to reduce stress, and help with his fin issues. You also need to tell us what and how much you feed, how often you do a water change, how much water you change, and your water parametres.