The Black-Lined Loach is peaceful, attractive, active and playful… a great all around aquarium fish!

The Black-Lined Loach Yasuhikotakia nigrolineata is a very active yet peaceful fish. They are not as shy of light as many Botias and will be out and about, playing during the day. A small group of these loaches will make an attractive addition to a community aquarium.

This loach is relatively new to the aquarium hobby, being first described as a separate species in 1987. Black-Lined Loach has two dark stripes, one running along the side from its nose to its tail and another close to the top of its body. As a juvenile it can have darker, chain-like, vertical markings between the two stripes. Its background color is lighter below the middle stripe and a darker golden tone above. Other common names it is known by are Negro Loach and Blackline Loach.

Some reports say that chain type markings can show up on the Black-Lined Loach when it reaches about 1 3/4″ in length, (though some reports say the Black-Lined Loach never has vertical markings). This chain type marking is common on its close relative the Dwarf Loach or Chain LoachYasuhikotakia sidthimunki. Neither of these two loaches have vertical markings once they mature, but the Black-Lined Loach is distinguished by having two horizontal stripes on each side while the Dwarf Loach has only one.

This loach enjoys the company of their own species and will do best in a group of five to seven, three is the suggested minimum to keep. For a comfortable home provide a soft substrate, some rocks and roots, and some plants. The water should be soft with regular changes. They are easy to care for and will eat any type of food that is provided, especially enjoying live and frozen worms.

The Dwarf Loach or Chain Loach, a once very popular fish, has become highly endangered and wild caught specimens are not available. These loaches are being captive bred, but not always readily available and can be expensive. The Black-Lined Loach is very similar in both appearance and behavior, and is much more accessible. This loach is a great substitution for the the aquarist.

Scientific Classification


Black-Lined Loach – Quick Aquarium Care

Aquarist Experience Level:Intermediate
Aquarium Hardiness:Moderately hardy
Minimum Tank Size:30 gal (114 L)
Size of fish – inches3.9 inches (10.01 cm)
Temperature:68.0 to 77.0° F (20.0 to 25.0&deg C)

Habitat: Distribution / Background

The Black-Lined Loach Yasuhikotakia nigrolineata, (previously Botia nigrolineata) was described by Kottelat and Chu in 1987. It is found in northern India, Thailand, and Laos. This species is listed on the IUCN Red List as Vulnerable (VU). It has a relatively widespread distribution, but populations are very fragmented and they are found in sparse quantities. It is suspected to have about a 30% decline in population due to hydropower development, over-collection, and habitat degradation in parts of its range. Other common names it is know by are Negro Loach and Blackline Loach.

This loach is considered the most northerly-distributed member of it genus and was first describes from the Mekong River. They are found in riffles of fast moving waters and in slow moving, or still waters. Its natural habitat is of moderately flowing rivers and streams has mostly sandy bottoms. It feeds on insect larvae and benthic organisms.

  • Scientific Name: Yasuhikotakia nigrolineata
  • Social Grouping: Groups
  • IUCN Red List: VU – Vulnerable


The Blackline Loach is a fairly small loach, not quite reach 4 inches (10 cm) in length, and generally have a lifespan of about 5 – 8 years, though it is thought they could live up to 10 years. This loach has two dark stripes; one running along the side from its nose to its tail and another close to the top of its body. Its background color is lighter below the middle stripe and a darker golden tone above.

  • Size of fish – inches: 3.9 inches (10.01 cm) – They are generally about 3.15 inches (8 cm) in length, but are reported to have reached up to 4 inches (10 cm).
  • Lifespan: 10 years – Their life span is usually about 5 – 8 years though it is thought they could live up to 10.

Fish Keeping Difficulty

The Black-Lined Loach can be hardy under the right conditions. They are not recommended for beginners because of their need for pristine water and having small body scales. Reduced scales makes them more prone to disease and very sensitive to medications used to treat disease. Experience in treating scaleless fish is very important to be able to give your loach a healthy and long life. Do not try to introduce these fish into biologically immature tanks.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate – They are very hardy fish but need an experienced keeper to maintain proper water levels.

Foods and Feeding

Since they are omnivorous, the Black-Lined Loach is not a picky eater. In nature this loach feeds primarily on insect larvae and benthic organisms, but in the aquarium it will generally eat all kinds of live foods, sinking pelleted and tablet foods, flakes, and algae. They like frozen foods as well. To keep a good balance give them a high quality flake or tablet food everyday. Feed mosquito larvae and brine shrimp (either live or frozen), tubifex, daphnia, and some vegetable foods such as algae wafers.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Occasionally
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

The most important thing for these loaches is that they always have clean and well-oxygenated water. Frequent water changes of about 30 – 50% a week are needed. With your weekly water change make sure to vacuum the gravel to remove all excess food and waste. Make sure not to remove the biofilm on rocks, decor or no viewing panes of the tank. A magnet algae cleaner normally does a great job in keeping the viewing pane clear.

  • Water Changes: Weekly – Water changes of about 30 – 50 % weekly.

Aquarium Setup

Unlike most of it genus which are bottom dwellers, the Black-Lined Loach tends to swim in the middle of the aquarium. Because these fish do best in groups, a larger tank of at least 30 gallons will work best.They do best in soft, slightly acidic water with low to moderate lighting.

Never introduce this Loach into a biological immature setup as these fish require pristine water. They also need good water movement that provides plenty of oxygenation. The tank should turnover at least 10-15 times per hour, powerheads and airstones can be introduced to achieve proper flow and oxygenation. An undergravel filter is a great choice for these fish as it creates high oxygen through out the tank as well as reducing the waste.

The decor with this fish is really up to personal taste as the fish doesn’t really pay much attention to it. If the tank is to resemble its natural habitat, sand and gravel mix would be best for the substrate. A lot of smooth water-worn large rocks and stones should be scattered throughout. A couple pieces of driftwood and some twisted roots will make a great place to retreat. These loaches are very inquisitive and like to explore so make sure to have a lot of caves and crevices. These fish can and will jump out of the tank if given the chance so make sure to have a tight fitting cover.

  • Minimum Tank Size: 30 gal (114 L)
  • Suitable for Nano Tank: No
  • Substrate Type: Sand/Gravel Mix
  • Lighting Needs: Moderate – normal lighting
  • Temperature: 68.0 to 77.0° F (20.0 to 25.0&deg C)
  • Range ph: 6.5-6.9
  • Hardness Range: 1 – 15 dGH
  • Brackish: No
  • Water Movement: Moderate
  • Water Region: Middle – Unlike most of its genus, which are bottom dwellers, this fish tends to swim in the middle of the aquarium.

Social Behaviors

These loaches make good community fish as they don’t demonstrate the nipping tendencies of some of their cousins. This being said it is still not advised to keep slow swimming long-finned fish with them. They are happiest when kept in a school of their own kind. A group of five to seven is suggested, with a minimum of three. They are also not as timid when it is light and are active and playful during the day.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species – conspecifics: Yes – Best in groups of 5 or more, with a minimum of 3.
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Monitor
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Threat
    • Large Aggressive, Predatory (): Threat
    • Monitor
    • Shrimps, Crabs, Snails: May be aggressive
    • Plants: Safe

Sexual differences

Sexually mature females are normally fuller-bodied and grow a little larger than males, while adult males develop slightly elongated snouts plus noticeably fleshy, thickened lips.

Breeding / Reproduction

Not much is known about the breeding habits of the Black-Lined Loach and they are not yet bred commercially.

  • Ease of Breeding: Unknown

Fish Diseases

Loaches are more susceptible to disease than other aquarium fishes. This may have to do with the faint body scales and no head scales. So take caution when introducing the Black-Lined Loach to an established tank. They are also very sensitive to different medications used to treat many diseases; a separate hospital tank is needed. Cold water and condition changes can also cause stress to this fish which makes them even more prone to disease.

Most common disease that affects this loach is Ich. Ich is short for Ichthyophthirius, also known as “white spot disease”. It is a parasite that can attack nearly all aquarium fishes, but you’ll find that loaches are often the first to be attacked. Take great care in treating ick as loaches are very sensitive to the medications used to treat it. Often the dose is half of what is normally used.

The second most common thing that affects loaches is a thing called skinny disease. This can be diagnosed fairly easily. If your loaches are eating a nitrous and healthy amounts and still seems to loose weight it is a good chance it has skinny disease. This is caused by internal parasites and can be treated with medication if used carefully.

An outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping these sensitive types of fish, it is common to catch deteriorating water conditions and disease before other fish are affected. The best way to proactively prevent disease is to give your Negro Loach the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish will is more likely to acquire disease.

Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


The Black-Lined Loach is becoming more readily available both in pet stores and online.



Featured Image Credit: Pavaphon Supanantananont, Shutterstock