Hey guys, Im an experienced aquarist having kept various tank configurations in the past, well as numerous Bettas and other labyrinth fish.
OK, a few things I would like to point out.
***** A bit of background info *****
The fish in question, "Betta Splendens" is whats called a labyrinth fish, meaning it has a labyrinth organ, which it uses to breathe air from the surface.
The fish should always have adequate space at the top of the bowl or tank to breath fresh air, and if the plant prevents this, remove or trim it.
The reason vases are unpopular among aquarists is because Betta Splendens is a top dwelling fish, and much of the vase's room goes to waste. It is important to have adequate surface area when keeping this fish, as it breaths air from the surface.
***** Plants with Bettas *****
Plants may introduce diseases and even toxins into the water, and you should consult your local fish shop about any plant you plan to introduce into your Betta's environment. Having said that, many freshwater aquatic plants are actually good for water quality, as they aerate the water and maintain a helpful culture of good bacteria in biomatter, accelerating the nitrogen cycle.
***** Cleaning the bowl *****
Betta's should not be kept in leaded glass crystal bowls, as the lead within the glass will leach into the bowl and poison the fish. If you keep your Betta in a vase, try to stick to the same procedure when cleaning it (yes, you have to clean vases too).
To clean the bowl, firstly fill a small container with water from the bowl, and put the fish and plant in it (try not to use a container that been exposed to detergent, soap or chemicals). Remove 2/3 of the water from the bowl, and scrub the glass using your hand. If there is gravel in the bowl, remove the gravel and rinse it in cold water. There is no need to scrub the gravel, as that would remove the good bacteria living in the gravel, impacting on the nitrogen cycle. Simply stir it up and poor the detritus out.
When the bowl is satisfactorily clean (it does not have to be crystal clear, most algae is not harmful for the fish), put the gravel back in. Remember to keep about 1/3 of the old water in the bowl. For the remaining 2/3, take cold tap water and treat it with a de-chlorination agent. These agents are inexpensive and are available from all fish and pet shops.
Never clean the bowl using soap or detergent. This is extremely dangerous for the fish, and will poison them.
***** Feeding your Betta *****
You should feed your Betta daily or every 2 days. I would certainly not recommend prolonging feeding for any longer than this, despite the fact that the fish can survive for weeks at a time without food. The amount you should feed the fish is the amount it can eat in about 20 seconds, without letting any go to waste.
Use special Betta pellets, and brine shrimp or bloodworms as a treat. Bettas are carnivores and will not live healthily on a purely vegetarian diet.
If the fish cant eat the food as you drop it in, you are over-feeding it. Fish naturally eat any food that is presented to them in the wild, as they never know when the next meal is going to come along. Because of this, a Betta will eat itself to death if you try to feed it until its full.
I think Ive covered just about everything
I hope this clears things up. E-mail me with any questions and Ill be sure to reply.
P.S. If theres an excess of bubbles appearing at the top of the bowl or vasedont worry. Your Betta is simply making a bubble-nest in which to breed. They even do this sometimes when no females are present.