Why does the Betta fish rub itself against glass of tank?

Exploring their surroundings: Bettas are curious fish and may rub against the glass to explore their surroundings. They may be exploring the reflection of themselves or objects outside the tank.

Stress or boredom: Rubbing against the glass can sometimes indicate that the Betta is stressed or bored. This can happen due to a variety of factors, such as poor water quality, overcrowding, or lack of mental stimulation.

Sickness or injury: In some cases, rubbing against the glass can also be a sign of sickness or injury. If you notice any other symptoms, such as changes in behavior, appetite, or appearance, it's important to consult a veterinarian.

Here are some things you can do to address this behavior:

1. Improve water quality: Make sure the water in the tank is clean and free of pollutants. Test the water regularly and make water changes as needed.

2. Reduce stress: Ensure that the tank is properly sized for your Betta and that it's not overcrowded. Provide hiding places and other forms of enrichment to keep your Betta entertained.

3. Rule out sickness: If you're concerned that your Betta may be sick, consult a veterinarian for a proper diagnosis and treatment.