Defensive:
* Flare its fins: This is a classic betta response. They spread their fins, especially their dorsal, anal, and caudal fins, to appear larger and more intimidating.
* Raise its gill covers: This makes them appear even larger and more imposing.
* Change color: Some bettas will darken their colors or develop a more intense red hue when threatened.
* Swim erratically: They might dart around the tank or hide behind plants or decorations.
* Build a bubble nest: This is a sign of stress and anxiety.
* Avoid other fish: They may try to stay away from other fish or even attack them if they feel cornered.
Aggressive:
* Charge at the perceived threat: This can involve biting, ramming, or even tail-biting.
* Spit bubbles: Bettas sometimes spit bubbles at the source of the threat. This is thought to be a form of intimidation or distraction.
* Shake its body: This is a sign of anger or aggression.
Other signs of stress:
* Loss of appetite: Bettas may stop eating or eat less if they are stressed.
* Lethargy: They may become less active and spend more time resting.
* Fin rot or other health issues: Chronic stress can weaken a betta's immune system and make them more susceptible to diseases.
It's important to note that every betta is different and will react differently to a perceived threat. Some bettas are more aggressive than others, and some are more prone to stress.
If you notice your betta exhibiting any of these behaviors, it's important to investigate the cause of the stress and take steps to address it. This could involve adjusting their tank environment, removing other fish, or providing them with more hiding places.