I can't say about the behavior.
Damsels are mean fish.
Do you have a test kit for water parameters?
Being new I'll guess your tank might not be cycled?
it is important to know where your water is at;
ammonia,nitrite and nitrates.
If cycled ammonia and nitrites will be 0.
If you have either then water change to reduce the ppm
to less then .75-1 ppm
The amount of water changedis the amount nutrients go down.
IE; 1ppm ammonia and a 50% water change should yield .5 ammonia.
What size tank?