This guide was created to gently support aquarists in understanding bottom-dwelling species as living, feeling members of the aquarium ecosystem—not just “clean-up crews.” Inside, you’ll learn how snails, shrimp, plecos, and loaches actually use space, what they truly need to thrive, and how to choose them ethically and confidently for your own tank.

In nature, fish don’t all swim in the same place — and that’s true in aquariums, too. Different species naturally prefer different areas of the water column: near the surface, through the middle, or along the bottom. This isn’t random behavior; it’s shaped by millions of years of evolution, feeding strategies, and safety instincts. This Guide explains in beginner understanding.