my poor betta fish

[joephone]

I have the new tank for two weeks now. My single betta fish is living with other tropical fishes, like tetra, swordtail and pleco. Never seen them fight.
However, today I see a while hole my my betta fish [photo attached].
The chemical test shows the water is ok, although I didn't add salt in it.
My betta fish is sleeping all day and not interested in food.

Any advice will be appreciated.

Thanks