Fit refers to how appropriate the elements of an environment are for a given environment. Being fit to an environment means that you have passed the standards and the requirements needed to survive in that environment. You can survive in that environment because the environment is suitable and right for you. Let us say for example, the fish would be fit to be in the environment with water since they have their gills which can be used to breathe in water. Cows are fit in a grassy environment since they usually eat grasses and some plants. Being fit is being suitable on the environment.
