My blue female crowntail Betta died today. My dad found her body partially covered by gravel. I did an ammonia test and got 0, and she had all peaceful tank mates so I doubt it was stress. However, she was extremely shy and barely ever came out; she would hide in the top of a plant almost constantly, but did seem healthy and did eat. I doubt these other things make a difference, but she was from a container at Petco and she was not in a small tank, she was in a 20 gal. What could have happened? 
