why does semen smell the way it does?

i have noticed semen has two scents.

the first scent is the ocean breeze scent that you smell when you first ejaculate. sometimes it smells like bleach too

the second is when its been sitting around for a while.. when it begins to smell like squid or rotting seafood.

i have no problem with the first kind, but the second one is truly annoying.
why does semen start to smell like that, and how can i prevent it or reduce the stench?

>>1
It smells after a while because of bacteria and other things in the air.  Essentially, the same reason urine smells if you don't flush your toilet.
But anyway LOL.  Take a shower once in a while.

P.S.  Mine smells like bleach after a while.