I change my bettas' tanks weekly, but this last time (3 days ago) Dale (my blue betta)'s tank got really murky. His behavior is not normal. He tends to stay on the bottom of his tank behind his plants. My other 2 betta (Chip and Minnie) have similar behavior but their tanks are clear. All 3 seem to be lethargic. They are all eating normally and reacting to the tricks I have taught them. I am really worried about Dale though. We just lost our blue crowntail Mickey a few weeks ago for no apparent reason. ANY help or suggestions would be GREATLY appreciated. Dale, Chip, and Minnie will thank you.