Is it okay to put deodorant under the foreskin to avoid fishy smell?

YES!

That is to say if you want to have some thing like cancer of the penis.

Which means you loose it!

No ew, just wash

No silly. Ladies do not like the taste of deodorant.

NO: you will cause your penis to become irritated ....

No.

It will irritate the sensitive Glans (head) of the penis.

Instead, try to be more diligent with your hygiene... wash your penis better.

Not a good idea. Try rinsing it out with peroxide before you shower, that will kill out most of the bacteria that actually causes the odor. Then rinse off well when in the shower.

No, it will dry out your penis and you could also have a bad reaction to it. The fishy smell comes from you not pulling your skin back all the way when you pee and not shaking it off good. It would also help to dab the end with toilet paper to make sure none of it stays in there. Even guys who don't have a foreskin can get that fishy smell if they don't shake it off or if they dribble in their underwear.

i dont like the taste

NO

Such questions are asked by persons who don't have a foreskin and know little about foreskin.

The inside of the foreskin should be washed occasionally with clear water without soap.

Smell occurs when the healthy bacteria that live under the foreskin are washed away. Frequent washing should be avoided.