Hillstream Loach Care Guide: Tank Mates, Size, Breeding…

A hillstream loach

The hillstream loach is an awesome looking freshwater fish that doesn’t get the attention it deserves.

Their special body shape and pattern make them really stand out from the crowd. If you’re looking for a unique critter to add to your tank, this is a good choice!

But they don’t just look really neat, they’re also quite easy to keep. There aren’t any big challenges you have to deal with when it comes to hillstream loach care, just maintain the appropriate water levels and they’ll be good to go!

In this guide, we’ll go over everything you need to know about the reticulated hillstream loach. Care instructions, tank mates, size info, you name it. Reading this will make you ready to purchase one yourself!

Quick Facts

Scientific Name:Sewellia lineolata
Other Names:Butterfly algae eater, butterfly hillstream loach, butterfly loach, butterfly pleco, Chinese butterfly loach, Chinese sucker
Lifespan:8-10 years
Size: 2-3 inches
Care: Easy
Diet: Omnivores
Water Conditions:68°F-75°F, 6.5 – 7.5, 
Medium hardness:Medium hardness
Tank Size:  50 gallons
Behavior: Calm and peaceful
Breeding Difficulty:High

Species Summary

The hillstream loach (scientific name: Sewellia lineolata) is from the Cobitoidea superfamily and Cypriniformes order. As a loach, they spend most of their time working their way around the bottom of rivers and creeks when in their natural habitat.

The reticulated hillstream loach is a huge fan of fast-moving water and is normally found in rivers and streams throughout Asia that have strong currents. If you’re in China, Southeast Asia, or India and see some speedy water, there’s a good chance a hillstream loach is in there!

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Author Note: Their penchant for strong fast-moving water is the main reason why they have such a unique look! They have very little hydrodynamic drag, which means they can easily navigate strong currents while other fish struggle.

In their natural habitat, a hillstream loach will spend their time either camped out on a rock or slowly working their way across the bottom looking for food.


The average hillstream loach lifespan is between 8-10 years if properly taken care of. Like all fish, this lifespan range can be impacted quite a bit depending on the level of care they receive.

With the hillstream loach in particular, your biggest focus should be on their water parameters if you want them to live long and happy lives. We’ll get into the details a bit further on in the guide, but that will have the biggest impact on their lifespan.


Where do we begin!

The appearance of the hillstream loach is incredibly unique and fun to look at. You’ll probably spend a good amount of time just staring at them!

Their unique look can sometimes cause confusion as to what exactly they are. These fish are sometimes called catfish or even mini-stingray (we can assure you they are neither).

We think the hillstream loach is a very beautiful fish. They have a very busy pattern that covers their entire bodies (including their fins).

The tiger hillstream loach has base coloration is a light grayish/yellow and thick black stripes go in random directions all over their body. These stripes are usually more linear on the caudal and dorsal fins.

The base coloration is a light grayish/yellow and thick black stripes go in random directions all over their body. These stripes are usually more linear on the caudal and dorsal fins.

Author Note: These fish do have barbels which are part of the reason why some people mistake them for a funky-looking catfish. These barbels are very short and small though and can be hard to notice from certain angles.

Their bodies are built perfectly to deal with fast currents. They have a nice tapered shape (kind of like a torpedo) that allows them to cut through and withstand water that moves quickly.

Reticulated hillstream loaches also have wing-like pectoral and pelvic fins that they use to move but also secure themselves onto rocks and various surfaces. This build makes it easy for them to resist currents while other fish are forced to use a significant amount of energy to stay in the same place.

When you look at the underside of this fish you’ll notice that they have a sucker mouth and a flattened belly.


The average hillstream loach size is between 2-3 inches in length. This tiny size makes it easy for them to find little crevices to hide in and access food that other fish can’t.

This doesn’t mean you’ll have trouble seeing this fish in your tank though. They will usually be front and center attaching themselves to the side of your aquarium, or on a rock surface.

Hillstream Loach Care

Hillstream loach care is all about making sure they have the proper water parameters and tank conditions. These fish are not finicky, and if you meet their basic needs they’ll be about as low-maintenance as it gets!

You’ll want to keep in mind their natural habitat when planning out their tank setup. While factors like water temperature and pH levels are things most aquarists are comfortable with, the current requirements can be a departure from many of the common freshwater fishes out there.

Tank Size

The recommended tank size for a hillstream loach is around 50 gallons. If you think it’s a little bit large considering how small these fish are, here’s the reason:

Author Note: These fish do best when kept in a group of 3-4. Also, their oxygen and water flow requirements mean it’s simply not possible to provide them with the conditions they need in a small tank.

Water Parameters

The base water parameters for a reticulated hillstream loach are fairly straightforward. These fish do better in cooler water which is useful if you plan on keeping them with other species.

They are reasonably hardy which means you do have some wiggle-room, but it’s best to keep them in water with the following levels.

  • Water temperature: Between 68°F and 75°F
  • pH levels: 6.5 to 7.5
  • Water hardness: Medium hardness

Make sure you perform regular water tests with a test kit to ensure that these levels are holding true. The best aquarists make this a habit because they know it’s far easier/safer to catch a level shift early on than deal with it later.

You’ll also want to aim for a water change once a week to keep the quality high. Hillstream loaches are used to the clean water that’s found in their natural habitats and can suffer in tanks with subpar water quality.

Current & Water Flow Requirements

In case you’ve been skimming, adequate water flow is incredibly important for these fish. There are a number of ways you can accomplish this, but the best is by using a powerhead to create a consistent and adjustable current.

This is also why the minimum tank size for a hillstream loach is bigger than you expect. You can’t generate a consistent yet non-disruptive flow of water in a tank that’s tiny!

Using a powerhead to create a current in your freshwater aquarium is not just for their preference either. In fact, we haven’t mentioned the most important reason why water flow is important.


Hillstream loaches need very oxygen-rich water in order to thrive. The complete lack of water flow can actually even kill them in some situations. 

In summary, keeping these fish in a tank without a current is simply not an option. 

What To Put In Their Tank

Since these fish spend so much time scouring the substrate, you’ll want to go with something soft and sandy. This will prevent them from getting cut or scratched when navigating your tank. Hillstream loaches have very smooth bodies so you should do what you can to protect them!

Something else you should consider adding to their tank is a series of smooth rocks. These make great surfaces for them to rest on and also tend to accumulate some algae over time that they can snack on.

These fish will also appreciate some good hiding places. Plants like hornwort are a great option, but feel free to experiment with a variety of other plants as well. Not only will they serve as a good place to get some privacy, but they’ll improve the water quality!

Other objects like driftwood and various decorations can make nice compliments to the tank too. We prefer to stick with a combination of plants and smooth rocks but don’t hesitate to do a little decorating!

Author Note: Hillstream loaches are very peaceful fish that want to mind their own business. Giving them a place to hide will help them feel comfortable and greatly reduce their stress levels.

Food & Diet

If you want your hillstream loach to live as long as possible then you need to make sure they have the right diet.

These fish are omnivores and spend most of their time in the wild scavenging and looking for anything suitable to nibble on. They have a very heavy amount of algae in their natural diet which is partly why they enjoy hanging out on rock surfaces so much (they are great places for algae to grow).

A well-balanced diet for a hillstream loach in captivity is a mi of flakes, pellets, algae wafers, frozen bloodworms, and brine shrimp.

You can also add in some vegetables for them like kale or spinach. There’s no guarantee that they’ll like it, but if they do it will provide them with a solid mix of additional vitamins and nutrients.

Hillstream loaches will also snack on algae that naturally occur in your aquarium too. You should view this as more of a cherry on top than something reliable. You don’t want to have a lot of algae in your tank, and there will rarely be enough to sustain these fish.

Author Note: Make sure you don’t give them flakes or pellets that are too large. Their mouths aren’t very large!

Behavior & Temperament

Hillstream loaches are a very peaceful and calm freshwater fish. They don’t want to start trouble with any other critters and prefer to spend their time scavenging for something to eat or latched onto a rock surface (or the glass in your tank).

It can be kind of funny to observe at times. It’s quite common to see all of your hillstream loaches attached to the glass of your tank without a care in the world. They just want to do their own thing!

However, it’s worth noting that these fish can exhibit territorial behavior in certain situations. This is why it’s usually best to keep their numbers at 3-4 in a 50-gallon tank. Exceeding this can lead to possible scuffles over territory.

Hillstream Loach Tank Mates

There are a number of potential hillstream loach tank mates you can choose from. The gentle nature of this fish means they really won’t want to get in the way of others.

They’re also a little too small to be much of a nuisance. They’re very aware of their diminutive figure and won’t push their luck with larger fish.

Danios and rasbora species are two very solid choices that we can recommend with confidence. They’ll get along very well with reticulated hillstream loaches.

Besides aggression, the main thing you’ll want to look for in a tank mate is temperature preference. Hillstream loaches like the water to be a little on the colder side so that rules out a lot of tropical freshwater fish. Always compare the recommended temperature ranges first just to be safe!


Breeding hillstream loaches is definitely possible but is known to be quite challenging. In order to pull it off, you need to agonize over water parameters and provide the perfect conditions. And even then, it might not happen.

The Process…

The males will try to attract the females by doing a little mating dance. If he proves himself, she’ll indicate that she’s interested by staying nearby him instead of going on about her business.

The male hillstream loach will then put together a nest by digging and sorting through the substrate. This is where the female will put her eggs. After fertilization, it takes a couple of weeks for hatching to begin.

You won’t need to separate the parents and the newborn fish after they’ve hatched. This is the one thing about breeding hillstream loaches that is actually fairly convenient. Everything else can be a game of trial and error though!


You can relax now, Hillstream Loach care is a fairly simple and stress-free process. These fish don’t need a lot of attention as long as you have their tank and water conditions right.

We’re huge fans of this fish because of their unique appearance and easygoing temperament. There’s something about watching them do their thing that’s so addictive. You’ll find yourself watching them way more than you expected!

If you have any additional questions about hillstream loaches we would be very interested in hearing from you. While you don’t need to have a ton of experience to care for them effectively, there are a few wrinkles that you might not be used to. We’re more than happy to help you figure them out!

Feel free to check out other care guides and don’t forget to tag us on Facebook when sharing cool photos of your Hillstream Loach!

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