Hillstream Loach: Complete Care Guide and Species Profile

hillstream loaches together on a rock
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: June 12, 2024
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If you’re looking for a coldwater fish known for its beautiful color changes, peaceful nature, and preference for hair algae, the hillstream loach is an ideal choice. Our detailed hillstream loach care guide covers everything from their dietary requirements to setting up their ideal tank environment. This guide is intended to provide you with all the crucial information necessary for their care.

Article Summary

  • Hillstream loaches have a unique body shape resembling a miniature stingray, contributing to their popularity.
  • Hillstream loaches should be fed once or twice a day with smaller, more frequent meals to replicate their natural scavenging behavior.
  • Successful breeding requires almost perfect water parameters, making it a task for experienced fish keepers.

Species Overview

Common namesHillstream loaches,tiger hillstream loach, river loaches, lizardfish
Scientific nameSewellia lineolata
SpeciesS. lineolata
Size2-3 in
Lifespan8-10 yr
FamilyBalitoridae
GenusSewellia
DistributionSoutheast Asia
ColorGray, green, yellow, brown
DietOmnivore
TemperamentPeaceful
Minimum tank size50 gallons
Place in the tankBottom
Care levelModerate
BreedingDifficult 

History and Background

The hillstream loach (Sewellia lineolata) is a freshwater fish that is called by many names- such as river loach and lizardfish- because of their unique body shape. Described in 1932 by S. Hora, this species was declared vulnerable on the IUCN red list in 2010 due to the rate of population decrease. The biggest threats to this species are overfishing and deforestation.

What is a hillstream loach?

The hillstream loach is a peaceful freshwater fish species. These fish spend a majority of their time along the bottom of rivers and creeks of their natural habitat.

Where did hillstream loaches come from?

Hillstream loaches are typically found in Southeast Asia, mainly Vietnam wherever there is oxygen rich and fast moving waterways. They were first documented by the scientific name, Sewellia lineolata, in 1932 by S. Hora.

Appearance 

Hillstream Loach Resting on a rock
(1) Hillstream Loach Resting On A Rock

Their unique appearance is partially what makes this species so popular. Although not the most brightly colored fish, their unusual body shape (looks like a miniature stingray) and barbels are sure to draw attention.

What do hillstream loaches look like? 

This bottom dwelling fish is very unusual in its appearance and are often wrongly labeled as other fish species. They have smooth and streamlined body that is light gray or yellow with dark brown spots splattered all over. Along the edges of their body the spots become more linear and look like an outline of their shape.

One fish species they are commonly mistaken for are catfish

One fish species they are commonly mistaken for are catfish as hillstream loaches also have barbels. Though used for similar purposes the hillstream loaches barbels are very short and difficult to see.

The reticulated hillstream loach has pelvic and pectoral fins that spread out to the sides much like wings. Not only does the horizontal fins allow them to catch a ride using fast flowing water it also allows them to hold onto smooth rocks and other surfaces in their natural habitat without difficulty.

How big does a hillstream loach get?

This fish species averages 2 to 3 inches long, about the same size as a pink rubber eraser or AA battery.

How fast do hillstream loaches grow?

This fish is slow growing and it can take them up to a year to reach their full size.

How to sex hillstream loach?

It is difficult to sex hillstream loaches as there are no visual clues and sexing is mainly based on differences of the fish’s body. In general females have a wider head and body whereas males have a jagged appearance due to their pectoral fins being close to their “shoulders.”

Temperament and Tankmates

A Planted Freshwater Aquarium With Different Fish Species
A Planted Freshwater Aquarium With Different Fish Species

Like most loach species, hillstream loaches are very peaceful fish and spend their time calmly exploring the tank and eating algae. This means they pair well with many other peaceful, freshwater species. This fish also does well amongst its own kind, and it is actually recommended that they be kept in small schools.

Behavior & Temperament

They are actually schooling fish and it’s not unusual to see all of them hanging on the glass or smooth rocks in your community tanks. It is worth noting that hillstream loaches, while schooling, will show territorial behavior if the school is too large. When choosing how many hillstream loaches to put in your tank it is advisable that you limit the school number to 3 or 4 fish.

What fish can live with hillstream loach?

Many other fish species are compatible with hillstream loaches though you should avoid any freshwater fish that have a reputation as a predatory fish.

Remember to check tank conditions compatibility in tank mates. Hillstream loaches prefer colder temperatures and high water flow. Small fish struggle to meet these requirements would not make good tank mates for this species.

Compatible Hillstream Loach Tank Mates

Compatible hillstream loach tank mates are not difficult to find but we’ve included some of our favorites below.

  1. Dwarf Shrimp – a cute and small freshwater shrimp that can assist your loach in cleaning up algae in the tank. Dwarf shrimp have a peaceful nature and will mostly mind their own business.
  2. Danios – a calm freshwater species and peaceful community fish that will easily adapt to the cooler water temperatures of a loach tank.
  3. Rasboras – if you’re looking to add more color to your loach tank, finding a brightly colored rasbora is the way to go. Some options include the emerald dwarf rasbora or the chili rasbora.
  4. Tetras-a schooling species that will mostly stay in the upper regions of your tank and not bother your loaches.
  5. Mystery Snails – a colorful, calm, and entertaining invertebrate that can coexist with your loach at the bottom of the tank.

Tank Mates to Avoid

The following do not make good hillstream loach tank mates. It is recommended you choose other fish or house these in a separate tank.

  1. Oscars – a tropical freshwater species that won’t do well in a loach tank due to their differences of water temperature needs
  2. African Cichlids -a well known aggressive fish they will relentlessly bully your hillstream loaches, likely chasing them to remote parts of the tank
  3. Barbs – a small but aggressive fish, a school of them can terrorize your loach.
  4. Vanmanenia – a more dominant genus of loach, avoid placing any of these with your hillstream loach or else they will be subjected to aggression
  5. Goldfish – while they are a non-aggressive fish species, goldfish can easily foul up your water quality. As loaches need a pristine environment they are not compatible.

Tank Requirements

Image of aquarium tank with a variety of aquatic plants inside
An Aquarium Tank With A Variety of Aquatic Plants

The biggest and most vital part of hillstream loach care is maintaining proper water requirements and a healthy tank environment by following the suggested parameters below.

Water Parameters

Tank Size>50 gal
Water typeFreshwater
Water temperature68-75
Water pH6.5-7.5
Water hardness3.5-7 dKH

Tank setup:

What kind of Substrate to use?

Hillstream loaches spend a majority of their time at the bottom of the tank. With their smooth bodies that are very prone to injuring themselves on sharp rocks or rough substrate, so choosing a fine gravel or soft sand substrate is best. Additionally, this fish enjoys burrowing to hide and search for food.

TIP

If you’re looking to make your fish tank into a planted aquarium be sure to include sturdy plants otherwise your hillstream loaches might damage the live plants by burrowing.

Do I need a Filter?

It is absolutely necessary to include a strong filtration system in your freshwater tank. Hillstream loaches live in a high quality environment and as such they have very specific water parameters.

Should I get a Pump?

Yes, the reticulated hillstream loach requires a freshwater aquarium that has a high circulation and fast flowing water.

Do I need a Water heater?

It is unlikely that you will need a water heater for this freshwater fish as they generally prefer a cooler environment.

What kind of lighting should I have?

While most hillstream loaches prefer dark hiding spots or caves your tank should have enough light to encourage algae growth and other biomatter. Most fish keepers suggest a 40 watt bulb to provide vegetation growth while not overwhelming your reticulated hillstream loaches or other fish.

RECOMMENDATION

Most fish prefer a light/dark cycle. Light hours should be 8 to 12 hours long, with darkness being 12 to 16 hours. This helps fish establish a natural sleep and REM cycle.

Do hillstream loaches need flow?

Yes, in their natural habitats hillstream loaches occupy places with fast flowing water. Tank conditions should meet similar standards. Part of the reason the minimum tank size is so large is because otherwise you wouldn’t be able to meet the standards of reticulated hillstream loaches.

Water flow requirements

Hillstream loaches thrive in an environment that has a strong current. As such you should plan on installing powerheads or air pump to your home aquarium and have it on the highest water flow setting or have it circulating at least 15x the amount of water in your freshwater aquarium.

TIP

The main reason adequate water flow is important for this species is because it provides a large amount of oxygen which this species needs.

Diet and Health

Variety of Fish Food
Variety of Fish Food

Feeding your fish a high quality diet and maintaining proper water parameters is the key to keeping your hillstream loaches happy and healthy. As omnivores, they’ll need a varied diet. Proper nutrition will also help this species to fight off common health issues such as ich and skinny disease. To learn more about how to properly conduct feedings and prevent illness, keep reading below.

What do hillstream loach eat

Hillstream loaches are omnivores, though a vast majority of their diet is centered around plant matter. In their natural environment hillstream loaches eat algae, insect larvae, plant matter, and small crustaceans such as daphnia.

What to feed hillstream loach?

In a freshwater aquarium you should try to replicate your hillstream loach’s natural diet as much as possible. A well balanced and nutritious diet would include blanched vegetables, brine shrimp, algae wafers, commercial fish flakes, insect larvae, and bloodworms.

How often to feed hillstream loach?

Hillstream loaches should be fed once or twice a day. As they are used to scavenging for their own food, smaller and more frequent meals will better replicate their natural eating patterns.

How much to feed hillstream loach?

Plan on feeding your hillstream loaches using the three minute method. This will ensure they’re not overeating while also allowing manageable clean up to prevent the fouling of your fish tank.

Common diseases of hillstream loach?

Skinny Disease

A common disease otherwise known as knifeback affects many loach species. This sickness is caused by an internal parasite (spironucleus) and symptoms include losing weight quickly.

The best treatment is prevention and you can use antiparasitics such as metronidazole or dewormers such as praziquantel to effectively get rid of any parasites before adding a fish to your tank. If your fish already has the disease you can use anti parasite medicine with active ingredients such as Levamisole HCl.

Fungal Infection

Fungal infections are very common when proper water parameters are not maintained, especially regarding temperature. Treatment for fungal infections include fish salt or aquarium salt, water changes, and antifungal medication.

It’s worth noting that fungal infections can be a secondary infection as a result of bacterial diseases such as ich. In this case both antifungal and antibacterial medicine would need to be used.

Ich

Due to their scaleless and smooth body, this species is susceptible to ich or the white spot disease. This disease is well known in the aquarium community and is easy to identify as infected fish are covered with white spots along their bodies and fins.

Treatment includes immediately quarantining the infected fish and performing at least a 30% water change, aquarium salt baths for the infected fish, and broad spectrum antibiotic medicine treatments.

How long do hillstream loaches live?

With ideal water parameters and excellent care strategies hillstream loaches can live upwards of 8 to 10 years.

TIP

If considering this species be sure you are prepared to take care of it for the full length of its life. Many people decide they don’t want their fish anymore and dump them into local waterways which can lead to invasive species and the degradation of the native habitat.

Breeding

A hillstream loach at the bottom of the tank with other fish species
(2) Hillstream Loach At The Bottom of the Tank

Breeding is quite difficult and is not recommended unless you are an experienced fish keeper willing to try something new.

Can you breed a hillstream loach?

Breeding hillstream loaches is technically possible but most fish keepers have a tough time succeeding in this endeavor. In fact to breed hillstream loaches you need almost perfect water parameters.

TIP

To promote reproduction raise the tank water temperature to 78 degrees and then cool it while feeding the parents an extra meal of protein each day.

How to breed a hillstream loach?

If you decide to pursue and start breeding hillstream loaches and are successful, you’ll notice that mating is initiated by male hillstream loaches doing a mating dance. If the female is satisfied she’ll stick around, otherwise she’ll carry about her own business.

Male hillstream loaches will build a nest at the bottom of the tank in preparation for the female to lay her eggs. Once she has spawned it will take 2 to 3 weeks for the eggs to hatch. Once the eggs hatch you’ll want to move the adult hillstream loaches to a different tank. If they remain in the same tank they are likely to eat their offspring.

What do hillstream loach eggs look like

Hillstream loaches lay eggs that are opaque or yellow-ish in color. They are extremely hard to see, especially when not laid on a dark surface. They are cylindrical.

Hillstream loach FAQS

Is a hillstream loach a pleco?

No, though it is a common misconception that adult hillstream loaches are plecos or catfish because of their barbels. While these appendages serve the same purpose the hillstream loaches have a much shorter barbel length than plecos do.

Is hillstream loach hardy?

Yes, the hillstream loach can handle a wide range of environmental conditions or withstand some changes to water quality but does need clean water to be healthy. Hillstream loach care is for aquarists that have kept fish before but are beginning to become more experienced and want a new challenge.

Where to buy hillstream loach?

Hillstream loaches can be purchased at your local pet store and are a beautiful fish to be able to add to your collection.

Why are hillstream loaches expensive? 

Hillstream loaches are one of the more expensive freshwater fish in the aquarium hobby mainly because they are very sought after as hillstream loach care is fairly simple.

Also contributing to their high price point is the fact that this species is difficult to breed in captivity.

Do Hillstream Loaches Clean the Tank?

Yes, hillstream loaches are an excellent addition to your tank cleanup crew as they will make quick work out of algal infestations such as hair algae or blackbeard algae. Just make sure that you are not completely on the algae to provide them with all of their food needs.

Will hillstream loaches eat fish?

Hillstream loaches will not eat other fish as their mouth is too small to be able to. These fish will mostly eat algae wafers and other small live foods such as brine shrimp or daphnia.

Do hillstream loaches have teeth?

No, this fist has a sucker mouth much like plecos and catfish. So you won’t have to worry about them nipping at your other fish.

Do hillstream loaches eat snails?

No, the peaceful temperament hillstream loaches are known for means that they will generally leave any living organism in the tank alone. Additionally, their mouth is too small to be able to eat a snail.

Can You Have Just One Hillstream Loach?

While it may be tempting to only have one hillstream loach so you can have a small tank, these fish are very social within their own species and prefer to be housed with others of their kind.

However, if you choose to get multiple loaches, purchase 3 to 5. If you place only two in the same aquarium they will compete and the stronger one will bully the weaker.

Is the hillstream loach for you?

If you’re looking for a fish to add to your cold water community tank the hillstream loach could be a perfect match for you.

Conclusion

These peaceful bottom feeders can be quite the fun and unusual addition to your aquarium. While they do require an intermediate level of care, you’re sure to fall in love with them for their sweet temperament and ability to clean even the most persistent of algaes from your tank. Continue to feed these fantastic fish a varied diet and provide them with clean, fast flowing water to ensure they thrive under your care. And be sure to share this hillstream loach care guide so all your friends can learn how to keep them too!

(1) Spiketooth, CC BY-SA 3.0, via Wikimedia Commons
(2) Mistumitsu, CC BY-SA 4.0, via Wikimedia Commons

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