How Many Cichlids In A 40 Gallon Tank?

Cichlids are known for being quite aggressive compared to other freshwater fish, not to mention that some of them can grow over one foot long. Having enough space in your tank depends on the type of cichlid, any other fish in the tank and how much decor you have. The good news is that you can create the perfect cichlid environment in a 40-gallon tank. But how many cichlids can you keep in a 40-gallon tank?

You can keep between six to nine cichlids in a 40-gallon tank, provided you choose the correct cichlids for the tank. As there are some cichlids, like the Julidochromis transcriptius that will only grow up to around 2.8 inches. A useful rule of thumb to use is two gallons per one inch of fish (fully grown) to determine the number of cichlids you can keep in your 40-gallon tank.

In this post, we’ll take a closer look at why you should limit the number of cichlids you can keep in a 40-gallon tank, the various types of cichlids you can put in your tank, and what other fish get along better with this aggressive species!

How Many Cichlids In A 40 Gallon Tank?

Up to nine cichlids can be in a 40-gallon tank, as long as the cichlids are a smaller species. You need to ensure that you have more than two gallons per one inch of fully grown cichlid to provide enough space for them to swim without the cichlids becoming overwhelmed or aggressive. Cichlids can quickly become territorial if they feel crowded by other fish.

Why you can’t fit too many cichlids in a mid-sized tank:

  • Cichlids are known for being territorial when overcrowded and will fight other fish to take over the tank.
  • Cichlids are some of the most aggressive freshwater fish you can put in a tank. Although generally, they won’t chase after each other as they’re more likely to fend for themselves rather than become territorial.
  • A common problem is that some cichlids can grow too big for a tank, while others need more space to roam without feeling crowded. That’s why it’s important to know what size your cichlids will get, to ensure your cichlids aren’t too big for your aquarium.
  • To give you a better idea of the types of cichlids, we’ll list some of the best species in the next section. It’s also important to let them swim around without being cramped or forced into a corner.
  • Something else to take into consideration is that cichlids poop a lot, meaning you’ll have a lot of cleaning to do if you have too many of them in a mid-sized tank. They do a lot of eating and pooping throughout the day, meaning that you’ll have to remove the waste to prevent the tank from getting too cloudy or unsanitary for the fish and plants that live in the tank.
  • These fish are well known for bullying each other and other fish if they outnumber them. They run into other fish, chasing them around the tank if the fish are too small or can’t defend themselves. It will become much more of a problem if you have too many cichlids paired with a tank that’s already overloaded with other fish.
  • Cichlids are very active, needing a lot of space to swim around. It’s why you’ll usually notice cichlids swimming from one side of the tank to the other all day (or night).

There are plenty of different cichlid species out there. Some cichlids are too big for a 55-gallon tank, never mind a 40-gallon tank. Knowing which species will survive and thrive in your 40-gallon tank will prevent them from becoming aggressive, or causing issues for other fish.

What’s The Best Cichlid For A 40 Gallon Tank?

The best cichlids for a 40-gallon aquarium are smaller cichlid species like the Julidochromis transcriptius, Kribensis, and ram cichlids, along with a few other species as they don’t grow bigger than four inches, making them a lot better for a 40-gallon tank.

Let’s get into the traits of cichlids that you can keep in your 40-gallon tank:

Julidochromis Transcriptius: These cichlids grow to around three inches, with the females typically growing bigger than the males. They’re one of the most popular cichlids due to them being small and easy to maintain.

Kribensis: These cichlids only grow slightly bigger than the Julidochromis Transcriptius, at around four inches in length. Contrary to the Julidochromis Transcriptius, the males grow bigger than the females (which usually get up to three inches). Keep in mind that these cichlids are more likely to breed in a mid-sized tank.

Ram Cichlids: are one of the smallest dwarf cichlids in the world at only around two to three inches long. Their vibrant orange, yellow, purple, and blue streaks can make them a good fit for all tank styles. Ram cichlids are perfect for those who want to fit as many cichlids in a 40-gallon tank as possible.

Apsitos: don’t grow much bigger than the Julidochromis Transcriptius. You can expect an Apsitos cichlid to get grow to around three inches long. The males are more noticeable having much more color on their skin than females, but both of them share a natural glow.

Can You Put Other Fish With Cichlids In A 40 Gallon Tank?

Yes, you can put other fish along with cichlids in a 40-gallon tank as long as there’s enough space and the fish aren’t aggressive. Some of the better fish to mix with cichlids include plecos and catfish, as they tend to mind their own business. They don’t go for the same food source, and they’ll be much lower in the tank than the cichlids.

You should consider these questions before introducing new fish to your cichlid tank:

What do the fish species eat? Cichlids are known to eat a variety of food including algae, plants, other tiny fish and larvae. If cichlids feel they’re not getting enough food, they’ll do their best to get rid of the competition. If you’re introducing new fish into the tank that eats the same diet, always ensure there’s enough to go around.

Are they as aggressive or territorial as cichlids and other fighting fish? It’s never a good idea to cram a bunch of aggressive fish in the same tank. Cichlids will often respect other cichlids, but they’ll group together and fight other fish species if they’re too territorial or try to fight them.

How big do the fish that you want to introduce get when they’re fully grown? You should limit your fish to one inch per two gallons of water, as mentioned a few times in this post. This rule applies to all fish, including cichlids.

Are they too small for the cichlids to mistake them for food? Fish like tetras can make for a delicious snack for cichlids, so they’re not the best combination. Similar tiny fish will be a cichlid’s dinner, so it’s always best to wait for them to fully grow before adding the cichlids to the aquarium.


While you may be able to fit a bunch of young cichlids in a 40-gallon tank, it will cause all sorts of problems later on. Choosing less aggressive fish along with an open habitat will provide a spacious, enjoyable living experience for the cichlids you want to add to your 40-gallon tank. Remember to pick smaller cichlid species so they won’t outgrow the tank.