parameters on betta bowls

While I was at fishkeeping chores yesterday, I thought to test the water in my Bettas' bowls. I've been thinking maybe I should change 50% of the water once midweek, in addition to the 100% change I do on fridays. To keep it clean enough. So on tuesday I tested, but everything was perfect. No bad levels. Today before cleaning I tested again. Quite surprised to find that the numbers were still all perfectly safe.

Pinkie's bowl had below 0.25 Ammonia, 0 Nitrites and only 5 Nitrates. This is amazingly good for an unfiltered bowl.

Flash had 0.25 Ammonia, 0 Nitrites and 10 Nitrates. Just as safe. Of course I did their water changes, but puzzled at how the bowls could be doing so well when I constantly read online and in books how unsuitable a bowl is for the fish, they really should be in an aquarium with a filter.

My fish have, for the most part, always seemed to do just fine. I think there are a number of reasons why this is working. There is a small layer of gravel in the bottom of each bowl, which probably at this point hosts some beneficial bacteria. Each fish also has a decor item with Java Moss tied on it, and Pinkie also has a fake plant. I always rinse debris out of the gravel with hot water, and rub the sides of the bowl clean, but I don't scrub the decor items. So I think that the surface of the decor, plants and gravel hosts just enough bacteria to handle the amount of waste from one fish. Plus I tried to feed them lightly, which keeps it from getting polluted, and the moss plant consumes Nitrates. It seems that even though I probably kill some bacteria when I rinse the gravel (it would be far worse to leave the food waste and fish poo in there) enough is alive in other areas of the bowl environment that things stay in balance.

At least, this is all what I think is going on. Someone do correct me if I'm wrong! Regardless, the fish seem healthy and content, the numbers are safe, and I am going to keep maintaining them this way until I can afford to house both bettas in filtered tanks. I feel like it is not good for the betta to be in such a small home; they would be better with more space and consistent heat (they stay just warm enough on top of my fridge, usually at 74° when I test the water but I know that a steady 78°-80° would be much better for them).

An interesting side note. I have noticed that Flash is definitely more feisty than Pinkie. When I approach the bowls all the fish swim to the near side to investigate. Pinkie moves back and forth curiously, but Flash displays and even flares his gill covers wide. When I set the test tubes near his bowl today for a photo, he swam back and forth in front of the glass where the tubes were set. It looked like he was displaying to the colors in the test tubes! I stepped back to make sure he wasn't displaying at me, and he kept darting back and forth near the colors. Flaring his gill covers as well which you can see in these shots:

My long-term plan is to integrate one of the bettas into my larger, community tank and to give the other one his own small tank. I will try at some point to see if Pinkie can safely coexist with the other fishes, but I think Flash is probably too aggressive and will have to have his own quarters!