Fish tanks and presence of rocks inside them

Every aquarium is a unique ecosystem and you will probably spend long months until you find two relatively similar fish tanks.

They come in a variety of colors and will grow very very large if you have a large enough tank. They say their max size is 6″, but I've seen them much larger in really large tanks.

Hi every one Im new to all of this but have some knowlege of setting up tanks and once had a brakish tank setup. I wanted to start a nano tank with some live rock and once cycled put in one fish.