Some well known benefits of planted fish tank -

Aeration - in planted aquarium, as in nature, the live plants provide all the oxygen your fish will ever need through photosynthesis. An airstone and air pump (and all the noise and vibration that go along with them) are unnecessary in a planted aquarium.

Filtration - live plants provide excellent chemical and biological filtration. They absorb chemicals that are harmful to fish (in fact they live off of the chemicals produced by fish waste) and provide a perfect medium for beneficial bacteria to grow on.

Protection - in fish only aquariums not having enough protection can cause fish to be stressed and more susceptible to disease. Although artificial decorations and plants can be bought and put in the aquarium to provide protection and cover for fish, they are inferior to real plants in many ways.

Algae Control and prevention - algae are often a problem in fish only aquariums, and although keeping algae eaters and scraping the glass with an algae scraper are ways of combating some algae, other types of algae are more stubborn. Algae occurs because there are nutrients in the water and there is light (even low light). In a planted aquarium, plants can outcompete algae and use up all of the nutrients in the water. In fact, once you get your planted aquarium balanced, you will most likely never have to clean the glass or pull algae off the gravel again.