u/Imaginary_Neck2335

Please help me how to save my betta!!

I just got few fishes and got 1 betta 3 days back he was new to the environment so it took a day to him being normal but this morning I saw him getting bullied by the gold fish in the tank i think they were messing with his fins so he stopped moving and just start floating top of tank without moving. Firstly I thought I loose him but then I notice his is taking air inside and fins are moving but very little so I separated him from others in a. Small box and added a little salt in the water. But I really don't know how to help him.

Can anybody help me out what to do and how to figure out what he needs right now.