Is my betta sick?

[CarpCharacin]

I have this betta in a 2.5 gallon tank. He is usually lethargic and his head almost looks sparkly but it does not look like a disease, but i am not sure what it is. The tank is not heated. He usually stays near the bottom and i don't see him eat, but he does when I'm not there. Most of my bettas have gotten lethargic after a while and then died maybe a year later. The oldest betta i had lived to 1 or 2. What exactly am i doing wrong?

 

[CarpCharacin]

I did a water change on the betta tank today, along with all of my other tanks.

 

[convict360]

2.5 is really small for a Betta, it's doable; but you have to really be on the ball with water parameters; it can be especially difficult to cycle these tanks as well.

Have you tested the water? You may see a large improvement upping him to a 6/7 gallon, but that's just a suggestion. The first thing I thought of when you said sparkly, would be velvet disease; but it would cover the body if it was that.

 

[CarpCharacin]

I am using a sponge filter and he is doing fine. He is more active since i put warm water in his tank. The water parameters are pretty good. The ammonia is lower than 0.25.