Freshwater Sand, Gravel, & Substrates

When it comes to freshwater tanks, you normally have two options—freshwater fish tank gravel or freshwater substrate sand.

Gravel substrate is a great choice for new fish keepers—the larger size of gravel allows water to flow through it easily. This means less buildup of bacteria. Your aquarium needs good bacteria to thrive, but too much can make your fish ill.

You have a variety of choices of freshwater aquarium gravel. There is an array of colors, styles and sizes to choose from. Gravel is a great choice for larger fish—many like to play with the gravel pieces and move them around in the aquarium.

Aquarium sand substrates can be great for our smaller fish friends who love to burrow and hide. It’s important to only use sand that was designed for aquarium use—it has special coatings to minimize interference of the habitat. Sand does need to be cleaned more often than gravel, but certain species of fish love to play in the sand and even consume a small amount to aid in their digestion.

When choosing your freshwater aquarium sand, remember that the finer the grain, the more bacteria will grow. It’s important to clean the sand regularly so your fish won’t get sick. If your tank is only going to house aquatic plants, you should choose a substrate that was designed for plant life.

A good rule of thumb is to use 1 lb. of freshwater aquarium substrate for every gallon of water for fish, though this can vary with aquarium size. You want to be careful with the depth—if it’s too deep, hydrogen sulfide may build and can be deadly to your fish.

If you’re raising aquatic plants, you’ll want to add more substrate so they have room to grow roots. They need around 2- to 3-inches of the substrate to flourish. This can vary with larger plants.

Which one you choose depends on what type of aquatic friends you’re adding to your habitat. It’s important to research your new pet to find out their likes, dislikes and must-haves to thrive. Our article How to Take Care of Freshwater Aquatic Life: Tips for New Fish Parents can also be helpful for new fish keepers or pet parents wanting to brush up on their skills.