get him a tank that is at least 2.5 gallon with a heater and a filter, problem solved
you need only to do 25% partial waterchange weekly, that’s it

Hope that helps
Good luck

EB

Just make the bowl a temporary home (I am sure that you knew as soon as you said bowl people were going to hound you to get a real aquarium!!) But you get a 2+ gallon tank and they now sell filters and heaters that will fi that tank perfictally her are some links for them (one that I prefer anyways!!): Thats the filter here is the heater: both are very inexpensive and you can find them at other stores too, plus your betta will be much hapier, and I think it would look a lot better and not mention cleaner!!! Hope I was of help to you!!!
~Kyle

The best thing you can do is go out and get one of those small plastic tanks that come with an undergravel filter, something about 2 or 3 gallons. Betta’s need proper filtered tanks, preferably heated (since they are tropical fish) for long term health, and it will certainly solve your water quality problem.

The only way to keep your fish bowl clean is to clean the water daily, or get your Betta a real tank with a heater and a filter. Keeping a Betta in a bowl with less than spotless maintenance can lead to ammonia poisoning and finrot.

Nosoop4u

happens to me too just change it and they don’t really mind it for too long but change it regualrly