How many milligrams of sodium should a 15 year old boy that weighs 125 lbs eat in a day?

I'm trying to avoid giving my 15 year old son processed food i try to feed him swai fish with unsalted sweet cream butter great value Walmart butter because i here margarines not really good for you and mrs dash for flavoring and ill let him put a very light layer of pink Himalayan salt over it Ive heard Himalayan salt has more minerals i don't remember if i got the salt from meijers or walmart but its pink and it has the name Himalayan on it but it doesn't list the minerals