Do Guppies Need Substrate? 10 Pros & Cons

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Substrate or no substrate? This is a common question that all fish keepers wrestle with since both options come with their own pros and cons.

Let’s see separate them so you can see which option fits your situation the best:

Pros and Cons of Having a Tank Substrate

Most aquarium owners will have different types of substrate, including sand, coral crumb, pebbles, rocks, etc. Each type of substrate will provide varying effects, and the main pros and cons include:

– Pros

  • Aesthetic factor – Aquariums with varying substrates tend to look more interesting than bare-bottom ones, and they give the impression of more natural habitat. In other words, this pro will most benefit you, the tank owner, thanks to the aesthetic factor it brings.
  • Good for aquarium plants – Plants with a substrate to anchor themselves into will grow larger and faster than those who don’t. Having a substrate is a must if you want a plant-filled tank with lush and thriving vegetation.
  • Accommodating bottom-dwelling fish species – We’re talking about scavengers like bristlenose pleco, catfish species, botia loaches, kuhli loaches, etc. These fish will spend their time in the tank’s lower areas, searching for leftover food from fish swimming in the tank’s medium-to-upper zones. The substrate will allow these fish to seek food and find shelter whenever they feel stressed or tired.

– Cons

  • Dirtier waters – Scavenger fish will ruffle up the substrate occasionally in search for food, sending torrents of dirt into the water. This can make the water tank look cloudy and dirty and muddy your guppies’ living environment.
  • More difficult to clean – You will have to vacuum the substrate occasionally if you want to maintain the tank water clean and fresh. The substrate will accumulate fish waste, which will increase ammonia levels, poisoning the tank’s water and all fish with it when not cleaned. This requires you to perform more regular tank maintenance to ensure the substrate hasn’t turned toxic.

Pros and Cons of Not Having a Tank Substrate

Many tank owners go for a minimalistic look, avoiding any type of tank substrate altogether. The pros and cons of this approach include:

– Pros

  • The cleaning job is easier – There’s no substrate to vacuum or replace once it gets too toxic. This makes the job of cleaning the tank’s bottom area a lot easier, minimizing your guppies’ discomfort.
  • Clearer water – The tank water will remain clearer for longer. You won’t have scavenger fish digging into the substrate and filling the water with particles anymore.
  • An overall healthier environment – Old and polluted substrates tend to affect the water’s chemistry, affecting your guppies in the long run. This is no longer an issue in substrate-less tanks.

– Cons

  • A minimalistic look – A fish tank will almost always look better with any type of substrate than one without.
  • Problematic environment for plantsAquarium plants can’t adapt too well to tanks lacking a proper substrate. This will affect the tank’s flora and will limit your choices when it comes to tank plants.
  • Problematic environment for fish – Many fish species depend on the substrate to find shelter, play, rest, or seek food. Taking that away from them will impact their comfort in the long run.

Which Substrate is Better for Guppies – Sand or Gravel?

Depending on your goals, you can make a compelling case for each of these substrate options. Here’s how these two types of substrates differ from one another, which are both good options for guppy fish tanks:

– Gravel Substrate

  • Prevents the buildup of harmful bacteria since water flows freely through the gravel particles, carrying bacteria through the filter
  • Gravel particles are heavier than sand, which means they’re unlikely to get sucked into the filter
  • Gravel is available in multiple colors, allowing for a higher degree of personalization

The problems with gravel

  • Food particles can fall between the gravel and decay inside the substrate, poisoning the water with time
  • Gravel requires more maintenance because of this

– Sand Substrate

  • A sandy substrate is more fitting for scavenger fish who like to bury themselves in the substrate
  • Sandy substrates are more natural-looking, creating a more beautiful aquatic environment
  • Sand particles are smaller, preventing food residues and fish waste from sinking in and decaying inside the substrate

The problems with sand

  • Sand particles are smaller and lighter, making it more likely to be sucked into the filter
  • Sand substrates are more difficult to clean and can make the water cloudy if disturbed by scavenger fish

Whichever you pick will depend on your goals and the fish species available in your tank.

How Often to Change the Substrate?

Fortunately, you don’t need to change your sandy or gravel substrate if you don’t want to. Even more, I would advise against changing it since the tank’s substrate will usually harbor cultures of beneficial bacteria that contribute to your tank’s healthy biofilm.

Cleaning the substrate regularly is enough to preserve the aquatic environment in optimal conditions with minimal effort. The frequency of cleaning depends on how big the tank is, how often you perform water changes, and how poopy your fish are. The latter matters because some fish will produce more waste than others, especially if you tend to feed them more than they need.

How Often to Vacuum the Substrate?

I recommend vacuuming the substrate every time you perform a water change. That would ideally be every week, or even more often, depending on your tank’s specifics. Smaller tanks or those containing an abundance of fish may require more frequent water changes.

At a minimum, you should vacuum the substrate once or twice per month. This is a reliable option for those with more stable aquatic environments.

Which Substrate is Better for Growing Plants?

The answer is easy – aquarium soil. This is an enriched type of substrate designed specifically for aquariums that comes with several benefits. One of them includes promoting plant growth, thanks to its nutrient-rich composition.

Be wary, however, since this substrate isn’t particularly ideal for live-bearing fish like guppies. This type of substrate doesn’t release enough minerals in the water to provide guppies with a safe and healthy environment. You could either enrich the tank’s water with minerals or use crushed coral on top of the soil to fix the issue.


To answer this article’s question conclusively, yes, I think guppies need some form of substrate. Having a substrate will allow the environment to mimic their natural habitat, providing guppies with a plus of comfort.

Not to mention, a well-maintained substrate will also allow you to keep scavenger fish, which will balance the environment and clean the substrate for you.

Updated: December 9, 2021
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