My betta fish lays vertically at the bottom of the tank barely moving, it looks like he's gasping for breath..

How old is he?

Their lifespan is about 3 years.

Information here about a sick Betta:

http://www.better-bettas.com/a/sick-betta-fish.sht...

When was your last water change?

FIrst off, airstones DO NOT add air to your bowl/tank. Change 1/2 the water immediately to add the Dissolved Oxygen back into your tank. This should help with the breathing. You will still need to do these water changes on a regular basis.

Also, TB is a very rare and contagious disease and very few fish get it. It isn't TB

Sounds also like your fish is suffering from a swim bladder problem. One thing at ta time. Change the water, see if that helps. Once your fish is up and swimming, feed it a few greens, peas, greenbeans, cukes spinach lettuce etc.

This should help

i would check the following:

1. temperature of the tank, too warm or too cold can cause lethargy and illness.

2. your last water change, as he's in an unfiltered tank by the sounds of it, this should be at least a 60% water change twice a week with dechlorinated water left to warm up to room temperature at least.

3. bettas don't need air pumps or air stones as they get a lot of their air from the surface anyway.

it sounds like he's come down with something, the inability to swim properly leads me to think a swimbladder problem, this can be caused by overfeeding, constipation or an internal infection.

give him a water change, lower the water level so it's easier for him to get to the top and remove the air stone if it's causing a lot of water movement. you can add a small amount of aquarium salt as this i've found boosts a fish who's sick, something scientific to do with electrolytes in their bodies.

keep his water clean and don't try and forcefeed him, if anything a few days of no food may help, then try him with cooked, deshelled pea (a fish laxative!). if hes showing any other signs of illness such as bloating, or losing weight, scales "pineconing", sores or white fluffy stuff on his scales, you may need to get medication for him. keep an eye on his cloudy eyes for now.

Bloating - constipation/overfeeding or a tumour if it's uneven

Losing Weight - internal infection or fish TB

Scales Pineconing - Dropsy, a secondary usually fatal condition caused by internal organs shutting down.

Sores - variety of reasons including injury, infection and fish TB

White Fluffy Stuff - fungus or columnaris

i swear by Melafix (half dose for bettas) which does say on the bottle it can help cloudy eyes and other external problems, but medications available can vary from country to country.

You probably haven't changed the water in the tank check your PH balance . The water Carry's oxygen, change about 1/4 of the water in the tank putting in Fresh water and see if that helps . Good Luck or you can always call a fish Dr we have one here in Calif and he's available 24 hrs and doesn't charge his customers maybe you have one in your city or call the store where you bought y our fish ... Good Luck :)