Kuhli Loach Tank Size Guide

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This guide to Kuhli Loach tank size will be useful to people who understand that Kuhlis are social fish that need to be kept in groups.

Therefore, it’s important to ensure two things:

  1. That you have a big enough group to avoid the Kuhlis feeling stressed
  2. That your tank is big enough to accommodate the amount of Kuhlis you decide to keep

Group size and tank size can’t be separated – the minimum tank size for Kuhli Loaches depends on the size of the group, and the maximum number of Kuhlis depends on the size of your tank.

One of my elusive Kuhli Loaches

What is the minimum tank size for Kuhli Loaches?

I recommend 20 gallons for a group of six Kuhli Loaches, which is the minimum number that should be kept together. A tank this size allows room for rocks, caves, plants, and decorations, which give your Kuhlis places to hide and shelter from the bright lights in your tank.

Because they’re largely nocturnal fish, their eyes can’t cope with intense light. Therefore it’s vital to give them these hiding places so they have somewhere to relax during the day.

It’s important to remember that all these items take up room in your tank, and reduce the number of Kuhlis accordingly.

How many Kuhli Loaches should be kept together?

The minimum number of Kuhli Loaches I recommend keeping together is six, but ideally ten or more. Kuhlis are super social fish and if there are too few of them in a group, they’ll become stressed and hide instead of feeling happy to come out and explore the tank.

They’re the most social fish I know and they’ll often be found laying on top of each other, rather than the kind of shoaling behavior seen in Neon Tetras, for example.

Unlike Tetras though, they’re bottom-dwellers and will hide amongst the rocks, plant roots, and other decorations in your tank for most of the day.

My Kuhli Loaches love to hang out around the rocks and plants at the back of the tank

They’re much more active at night, and in the right group size and tank, they display some entertaining behavior when they come out to play!

Here’s what you need to know to make sure they’re happy with the size of your tank.

Kuhli Loach tank size guide

Firstly, Kuhlis are bottom-dwellers as mentioned, which means a high tank with lots of space is wasted on them.

If you go for a wider tank with less height, the loaches will have more space in the area of the tank they actually occupy.

With this in mind, here is a table showing the minimum Kuhli Loach tank size by group size, in liters and US gallons:

Tank Size (US Gallons)Tank Size (Liters)Kuhli Loach Group Size (Max)

How many Kuhli Loaches in a 10-gallon tank?

A 10-gallon tank with no rocks, caves, plants, and decorations added wouldn’t be a suitable environment for your Kuhlis, as they’d have nowhere to hide from the bright lights. They also wouldn’t have any hiding places if they felt threatened.

On the other hand, if you add rocks, caves and other decorations to a 10-gallon, those items all take up space. This means there are no longer 10 gallons of water in the tank, so it’s still unsuitable.

If you want to add other fish as tank mates for your Kuhli Loaches, you’d need even more space. 

Additional fish means more bioload, even if they’re small surface dwellers like Guppies who wouldn’t be close to your Kuhlis.

The more bioload (the waste produced by your fish), the more ammonia is released into your tank. Ammonia is toxic to fish and can cause illness and even death.

A bigger tank means the ammonia is diluted. A good filter and regular water changes will then protect your fish from toxicity in the tank water.

Note: understanding ammonia is simple – you should aim for 0 ppm. However, if you want to know about pH, general hardness and temperature, check out this guide to water parameters for Kuhli Loaches.

Can I keep a Kuhli Loach in a 5-gallon?

A 5-gallon tank is too small for Kuhli Loaches. Kuhlis can’t be kept alone because they’re social fish who will be stressed if not kept in a big enough group. 5 gallons is far too small for even one Kuhli Loach, as they grow up to 4 inches in length.

This is why 5 gallons isn’t included as an option on the table above. If you only have a 5-gallon tank available, there are lots of other nano fish you can keep, including a male Betta which is more than suitable for a 5-gallon tank.

Photo by DruidSpider on Reddit

How many Kuhli Loaches in a 15-gallon tank?

It’s theoretically possible to keep a group of six Kuhli Loaches in a 15-gallon tank, but I wouldn’t recommend it. It would be difficult to give your Kuhlis enough hiding spaces like rocks and caves in a 15-gallon without taking up the swimming space they need.

If you really want to keep Kuhli Loaches (and I don’t blame you!) try to get at least a 20-gallon tank. And remember that wider is better than taller, as all the various types of Kuhli Loaches are bottom dwellers who never really swim to the middle or top of the tank.

If you only have a 15-gallon tank, I’d recommend a group of 8-9 Neon Tetras. They’re an amazing nano fish who display some really cool shoaling behavior.

You can find out about the ideal tank size for Neon Tetras here.

How many Kuhli Loaches in a 20-gallon (long)?

You can easily keep six Kuhli Loaches in a 20-gallon tank along with everything else they need to live their best life. A 20-gallon tank leaves plenty of room to add plants, rocks, caves, and other decorations, which Kuhlis need to feel safe and provide shelter.

You’ll be able to add these into the tank without losing too much space for your Kuhli Loaches. Rocks take up lots of space in a tank, but my Kuhlis love to relax in the shadows they create.

It’s also a good idea to put caves in the tank for them to hide in during the day, when the tank lights are on. As mentioned above, Kuhli Loaches are mostly nocturnal and bright lights can damage their eyes.

Finally, plants are great for Kuhli Loaches, especially those with lots of roots and stems for them to hide in.

I have anubias plants whose roots rot if planted too deeply in the substrate. This makes them perfect for my Kuhlis, who wind themselves between the roots and shelter under the shade of the thick, broad leaves.

Remember, Kuhli Loaches are bottom-dwellers so a high tank isn’t as good for them as a long one. In a wider tank, they’ll have more room in the area of the tank where they spend most of their time.

This 20-gallon long is ideal:

A 20-gallon tank with this kind of setup can even accommodate a small group of other fish as tank mates.

Small, peaceful fish that spend most of their time at the surface or around the middle of the tank would make the perfect tank mates for Kuhli Loaches.

How many Kuhli Loaches in a 29-gallon?

A 29-gallon tank is a perfect home for around 15 Kuhli Loaches. With nothing added to the tank, a 29-gallon will be at around 65% capacity, which leaves room to add rocks, caves, and plants to give your Kuhlis some hiding places and shade from the tank lights.

This setup also leaves room in case your Kuhli Loaches breed, or if you decide to add a small group of nano fish as tank mates. Shrimp and snails also add little bioload and can be added to the tank’s cleanup crew of bottom-feeders.

How many Kuhli Loaches in a 55-gallon?

You can keep around 20 Kuhli Loaches together in a 55-gallon tank. A group of this size will be really happy as Kuhlis are an incredibly social fish, and a 55-gallon tank is perfect as you’ll have enough room to add rocks, caves, and plants to provide shelter.

As with any Kuhli Loach tank, you can’t stock it to the limit of the tank’s capacity alone as you need to consider how much space will be taken up by the rocks and other decorations that Kuhlis need.

Before adding any of these items, your 55-gallon will be at about 60% capacity with 20 Kuhli Loaches. This gives you plenty of room to add the plants, rocks and caves they need for hiding places when they feel threatened, or for shade when the tank lights are on.


Kuhli Loaches are a shy, unusual but entertaining fish to keep in a dedicated tank or as part of a community.

However, as with any social fish, it’s important to keep them in an appropriately-sized group. Just as important, give them a tank that can accommodate the group’s bioload and give them enough swimming space.

The perfect Kuhli Loach tank size is a 20-gallon long for a group of six, with some rocks and caves for shelter. I’d also add some tall plants like Amazon Sword to provide shade from the bright lights, and some anubias or similar at the bottom, where the Kuhlis can chill out amongst the roots.

When it comes to tank mates, Kuhli Loaches can live with a wide variety of freshwater fish because they’re such a peaceful species and as bottom-dwellers, they stay out of the way.

I always recommend checking AqAdvisor to make sure your fish are compatible and that your tank can accommodate the community you’re trying to set up.

In the meantime, if you have any other questions about these wonderful fish, you’ll find everything you could possibly need to know in this Kuhli Loach care guide.

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