"Currents affect fish by bringing in rubbish, dirty water, and other stuff"
yes they do it has pressure witch does not make water smooth i do not think you would like it if you were a fish
Currents cause marine life to be pushed around, that's why fish are sometimes on shore.
Lava lamps.
the effect is that the currents slowly start killing fish by pushing them onto shore
they dont
it affects everything
Convection currents occur in the mantle of the earth. They can affect the crust and the life above it, though.
It's more likely the other way around. Ocean currents affect ocean life. Perhaps in a subtle way, since all life on the planet affects the atmosphere, especially the algae in the oceans releasing oxygen, that ocean life affects the weather, which in turn affects the ocean currents. It's also possible that some "seaweed forests" slow the movement of currents.
climate marine life
It gives us hot and cold temperatures on earth.
Warm currents have a very obvious affect on the temperature that surrounds it. Warm currents will warm the area around the currents.
Tsunamis can affect marine life by moving their habitats. For instance, if the water a fish is in move to shore, then the fish will move with it.