Why are plants and algae important in an aquarium?

The importance of plant and algae vary.When you first put in all these plants,you think it is JUST for decoration.But it is very important!The fish and snails are familiar with these types of plants.They eat the plants and gain their energy from it.The plants also give off useful oxygen.Without the oxygen,The fish would pretty much be dead.Another good purpose for the plants is one of the most important.The elodea and some other plants hold on to the dirt,so they pretty much filter the water,so when the fish and snails the plants,they are eating the gunk and dirt.It all gets put together when you really find the purpose of the plants in an aquarium.