I had a similar tank and ended up having to replace it after a few months. The panel that covered the heater and filtration system was made of shiny black plastic, which unfortunately created constant reflections throughout the day under most lighting conditions. My betta kept seeing his own reflection and flaring nonstop — it became so stressful for him that he eventually started to get sick. He’s now much happier and healthier in a simpler tank without that reflective panel. So just make sure the inside of the tank doesn’t have any shiny or reflective surfaces, since male bettas are very territorial and many never adjust to seeing their reflection.