I thank you for your concerns. My two bettas are just fine in this tank, it is filtered, heated and has twice weekly water changes done to it. I have been keeping tropical for over 20+ years and many bettas also in that time. These two super deltas are very healthy and do alot of swimming in this tank and are fed a variety of many different kinds of foods each day.
If one were to really look at the big picture of keeping fish today, we are all keeping them in confined spaces (aquariums) as appose to where they should be kept. Big open bodies of water. Weather its the saltwater hobby or the freshwater hobby, nothing will ever take place of their natural areas. So we provide mini oceans and mini freshwater areas for them so we can enjoy them all in our homes.
The most important thing in this hobby is to make sure you provide them with good clean aquariums and a varied diet.
My longest lived betta in a tank this size was 4 1/2 years old from a small baby to adult size. Thanks for your concerns but my fish are in very good hands.