Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

How Many Bristlenose Plecos Can Live in a 20-Gallon Tank? Vet-Verified Stocking Info

Brooke Billingsley

By Brooke Billingsley

bristlenosed pleco

Vet approved

Dr. Luqman Javed Photo

Reviewed & Fact-Checked By

Dr. Luqman Javed

DVM (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

Learn more »

Bristlenose plecos (Ancistrus) are one of the most popular plecos that you’ll spot in home aquariums. As people learn more about how large the common pleco can get, they’ve begun searching for a better alternative, which has led many people to the cute little bristle nose. With the small size of the bristle nose pleco—maxing out around 4-5 inches in length—some people may unintentionally keep their fish in tanks that are too small. Although small, there shouldn’t be more than one or two Bristlenoses in a 20-gallon tank.

aquarium plant divider

What’s the Minimum Tank Size for a Bristlenose Pleco?

Bristle noses may be relatively small fish, but they do still need space, on top of having a relatively heavy bioload for their small size. The ideal tank size for a single bristlenose is 20 gallons, but one can be kept in a 15-gallon tank with proper filtration. While they are peaceful fish, they can become territorial as they age, especially if they’re males. Because of this, each fish will need enough space to have their own space and territory.

Bristlenose Pleco catfish in the aquarium tank at local pet store
Image By: haireena, Shutterstock

How Many Bristlenose Plecos Should Live Together?

While Bristlenoses can live in groups when they’re young, they are generally solitary animals, so keeping them in groups isn’t necessary. Some people do enjoy keeping more than one bristlenose pleco, though, which can be done with enough space. Anywhere from two to five bristlenoses can be kept in a tank together, but they should be provided with enough space. Aim to stick to around 20 gallons for the first Bristlenose pleco, and around 10–15 gallons per additional Bristlenose pleco to keep your fish comfortable and healthy. Therefore, a group of five bristlenoses should have at least 55–60 gallons of tank space.

What Kind of Filtration Does a Bristlenose Pleco Need?

Since they can produce a somewhat heavy bioload in their tank, it’s important to ensure you provide your Bristlenose with adequate filtration. The filter should be rated at least for the size of the tank if you have one Bristlenose. For multiple Bristlenose plecos sharing a tank, you may need to upgrade to a filtration system that is rated for a larger tank than the size of the tank your fish are in. For a 20-gallon tank with two Bristlenoses in it, it would be best to have a filtration system rated for a tank that is at least 40 gallons.

A bristlenose pleco in a gravel lined tank, in front of the open mouth of a semi-buried plant pot

aquarium plant divider

In Conclusion

While there are no hard and fast rules when it comes to aquarium stocking, it’s important to consider the needs of your fish above your own vision for your tank. This means that you will be limited in the number and type of fish you can keep in a smaller tank. The size of the Bristlenose makes it appropriate for tanks as small as 15 gallons, but this may be too small in a tank that is stocked with other animals. It’s therefore best to play it safe and spring for a 20-gallon tank for these fish.


Featured Image Credit: TTONN, Shutterstock

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database

Shopping cart0
There are no products in the cart!