I don't understand why people feel a strong hatred towards betta fish in bowls. I understand that its very cramped in such a space but you can maintain it healthy and happy under lets say at least a 1.5 GAL or more. As long as you have your water readings within desirable levels. I have many betta books from TFH and it remains one of my favorite fish. I dont encourage them to be kept in vases but with very strict water changes every 3 days at the least and scooping any waste/uneaten food at the end of the day you can manage. I have one female betta in a 2 gallon high vase which is almost 3 years old now and still looks great. It is very hard to maintain water quality pristine in small quantities but if u use RO water or can afford to have such a unit even better. I use RO water in all my tanks. I have a 6 year old betta in a 10 gallon planted tank running with an Aquaclear 70 at minimum flow rate of 100 GPH and filtration set at minimum flow rate develops bacteria better. I am a firm believer in all the tanks i have to have the highest filtration i can fit with minimum flow rate that does not harm my fish. That tanks i own even with a filter gets small water changes every 3 days and the betta's i have along with the other fish have a wide diet from Blood worms, tubifix worms, krill, and hikari micro pellets and wafers, etc. In conclusion i never recommend a beginner start off with a vase as it is not something they can maintain running so well since they don't have great experience with fish tanks.
We feel a strong hatred (well at least I do), because there are a lot of ignorant people out there who just feel that they can plop a fish in some water, feed it once a day and it will live forever. Bowls do not help this at all, as they are still the major driving force behind the number one cause of captive fish deaths in the world, new tank syndrome, however in an unfiltered bowl, it never gets past the ammonia stage, keeping it in a perpetual state of pure agony for fish.
That is why I hate bowls, and if companies would put fish before profit for a change, we might be able to make a difference. This is what I do in my area of England, I go to different stores and challenge them on why they sell these items. The smaller stores have no defence, often leading with "it's only a fish", at which point I normally get thrown out of the store.
To me, selling a bowl or a vase for the expressed purpose of putting fish in it is one of the worst aquatic-sins you could ever possibly do. If you do decide to put a fish in a bowl/vase without a filter, you better make #41#### sure you do at least a 95% water change every day or I will personally take that fish off you (at least in this area).