Betta fish are strickly carnivores.
They'll totally thrive on a regulated diet of live fish food (e.g. mosquito larva, brine shrimp, daphnia, snails) and all sorts of live worms. The thing to remember is: *DON'T* over feed them. You should try and limit their feeding time to a portion which they can digest in less than say one minute.
Another good idea is to let your Betta pet go on a fast for say one day a week. This provides your Betta an opportunity to clean out its digestive tract and internal organs.
A Word About Worms and Gravel
While gravel can effective and attractive it can harbor deadly bacteria. Plus worms tend to hide in the gravel. Remember that your pet Betta can't eat the worms if he or she can't locate them.
So too is any uneaten fish food pellets which can get mixed in with the gravel and is hard for your Betta pet to find. Not to mention that this uneaten food can't be easily removed from the Bettas tank therefore it has a tendency to pollute the water over time.
This of course, will result in a cloudy unhealthy water environment. Plus gravel can add extra maintenance (and, cleaning!) to your "Must Do" list.
A Word About Plants
You need healthy live plants. Why? Because they not only look good but... they will give your pet Betta fish places to hide. Plants that are dead and sick plants create serious water problems another thing you should watch out for.
If you decide to use artificial plants (in lue of natural living plants) consider using silk not plastic, because plastic plants tend to have sharp edges and can damage your betta's glorious fins.
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