My Betta Fish stays at the bottom of the tank and just comes up for air

[Beeta12]

Hello everyone!

I bought my betta fish a week an a half ago. I've changed the water twice so far, the second time being about 1hr before this post. After the water change, my fish is just staying at the bottom of his tank and just coming up for air. Would this be because of temp shock? Or is he scared from being moved around so much? I fed him some pellets earlier today so I don't want to feed him again until at least late tomorrow. What do you think happened? Could he be trying to sleep...?

Sorry, I'm not really sure how this works and would like to know your insight so I know what to expect.

I have a .5gallon tank. He was fine and active for the past week so not really sure what changed.

Thank you so much!!

[AQUALUVA]

Did you say 5 gallon? Have you checked the temp or ph

[aokashi]

a .5 gallon is really too small. and ideally you should be doing 100% water changes everyday or every other day....
do you have a heater?
Do you know what the tank temperature is..?
Can you also describe your feeding schedule?

[Tikibirds]

did you just plop the fish back into the tank or did you slowly acclimate him.
Also do you use water conditioner?

I suggest at least a 1 gallon, ideally 3ish gallons is even better. Since they are tropical fish, they really should have a heater and a .5 is almost impossible to heat. Even a 1 gallon is hard because most heaters are too tall to fit into the tank or they will overheat the tank.