Choosing Substrate for Your Aquarium

For the sake of simplicity this article will address substrate choices for a freshwater, non-planted tank.
Appearance is often the main focus when choosing substrate, however there are other factors that should be considered.

Substrates come in all sizes and colors.

      • What type of fish do you plan to keep?
      • Particle Size
      • Color
      • Do you want your substrate inert, or to react with water?
      • Gravel vs. sand.
      • What about bare-bottomed tanks?


The type of fish you plan to keep is a major factor in your choice. Will you keep bottom dwellers that like to burrow such as some Corys and loaches? Or ones that scoot across the bottom quickly such as Pictus cats? For these fish very smooth gravel in the range of 3.00mm to 5.00mm would be ideal. Gravel this size can also be vacuumed easily. If you prefer aquarium sand it can also be used for these types of fish. Sand can be more difficult to vacuum, however. Do you want to keep African Cichlids? Then your choice would be crushed coral, coral sand, crushed limestone or aragonite as these have buffering capabilities that maintain a higher PH, and increase water hardness, which is what these cichlids need. Something such as this would be a very poor choice for angelfish or discus as they prefer softer water and much lower PH. Some fish enjoy making “nests” or “mountains”, in this case you’d want a smaller particle size. Under no circumstance should colored glass chips be used, the edges are far too sharp.


Like many bottom dwellers Pictus cats need a fine substrate

Are you a beginner hobbyist? If so, your best choice would be inert small gravel, as the majority of beginner fish do not require any substrate with buffering capabilities, and it’s best to use this while you are learning to keep your water parameters in spec.

What color? The possibilities are almost endless. The color you choose will impact the well-being of your fish. Some fish actually prefer a lighter or darker shade and their color will change accordingly. Again, do your research. You will be able to find something that doesn’t spook your fish and is pleasing to you also. It’s almost never a good idea to choose bright neon colors that your fish would never see in the wild.

Bare-bottomed tanks can be useful as it is very easy to see detritus and uneaten food and vacuum it up. The shiny, reflective bottom can startle your fish however. This is not a good choice for fish that like to burrow or dig as the lack of substrate will stress them. If you choose this route, there are many ways to create the look of a bottom without having actual material in the tank. Natural stone flooring can be applied in the upper part of you tank stand, giving it a natural appearance without having to vacuum around anything.

How much do you need? A rule of thumb is 1 lb per gallon to achieve a 1″ bed. Or 2 lbs per gallon for a 2″ bed. I’ve found the shallower beds to be easier to vacuum and keep clean.
No matter what you choose, make sure you thoroughly rinse it first. Just to be safe, on your last rinse, take the water level down to the top of the substrate and add a couple drops of de-chlorinator.

The bottom line is to thoroughly research your intended fish purchases and find something that matches their requirements. You will be sure to find something that is appealing to you as well, that both you and your fish can enjoy for years.

5/5 - (16 votes)


Please enter your comment!
Please enter your name here