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?

The /b/tards are fat, ugly, stinky, ignorant, unproductive, obsessed with Japan, atheist, wear glasses, and have long hair. Except some skinny /b/tards who are incapable of gaining muscle or weight and one poke will break their fragile weak bones. They are going to Hell.