A word of advice for anyone who keeps wild bettas. If you are using a Box Filter, make sure you have netting or some obstruction to prevent the Bettas from traveling down the Air Exhaust tube while allowing the air to come out. That is unless you don't care if the betta turns the bottom of your Box filter into his or her home. I found one of my Betta Rutilans moving in and out of the exhaust tube on the box filter and he was living happily in the small water space at the bottom of the the filter, so I dimantled the filter and removed him, much to his annoyance. These fish are so skinny that they can squeeze into almost any tight space so they require special attention to details. The fact that the filter air flow has to be fairly slow for still water fish like Bettas makes the odds of this happening greater with these types of fish. I'm not sure if the betta were to lay eggs in the bottom of the box filter and if they were fertilized and hatched how this would affect the fry. They would probably have plenty of microscopic food at least for a while. I am constantly amazed at the antics of fish.
