Black beard and hissing are common Bearded Dragon Behaviors and can be caused by various factors. These include territorial displays, Aggressive Beardie, aggression towards other animals, missing the previous owner, or feeling threatened. It's essential to observe their environment for potential triggers such as glass surfing, aggressive behavior, or encounters with wild or dominant animals. Additionally, ensure the temperature in Bearded Dragon Tank is optimal using a digital thermometer and provide a suitable habitat to reduce stress. If you notice persistent aggression, Bearded Dragon Bites, or concerning behaviors in your Pet Dragons, consulting with a reptile expert can provide guidance and support.