Vaillantellidae

Dragon Loach

Vaillantella maassi

The Dragon Loach, also known as the Chocolate Loach, belongs to the family Vaillantellidae and is classified under the scientific name Vaillantella maassi. It is not uncommon to find a direct transliteration of the Latin name in Russian — Vaillantella maassi.

Tank
from 108 L (29 gal)
Temperature
23 – 29 °C (73 – 84 °F)
Size in aquarium
12 cm (4.7 in)
Acidity
pH 3.5–7.5
Natural rangeRange on the map
  • Kalimantan area
  • Sumatra area
  • Brunei
  • Indonesia
  • Malaysia

Tank conditions

Plan the tank stocking
Temperature
23 – 29 °C (73 – 84 °F)
Water pH
Acidic (3.5) – Neutral (7.5)
Water dH
Very soft (0) – Hard (12)
Water salinity
no salt (freshwater)
Size in aquarium
12 cm (4.7 in)
Lifespan
5 years
Temperament
Territorial often aggressive
Toward small fish
not a predator
Required aquarium volume
from 108 L (29 gal)
Lighting
dimmed
Substrate
fine sand
Water flow
weak
Feeding
Mixed diet meat + plant-based
Keeping
Solitary
  • Lifespan. A lifespan to expect under good care, not a measured value: it depends heavily on tank volume, water quality and diet — and for selectively bred forms, on their origin as well.
  • Toward small fish. Based on the Predators category in the catalog or the temperament in the species parameters. “A risk to small fish” means the species is not a predator by habit, yet will swallow any fish that fits in its mouth.
  • Required aquarium volume. This is a husbandry recommendation, not a measured value: the volume depends on the keeping mode (solitary), footprint, decor and tank mates.

Care and keeping

Description

Adults of this species reach a length of 10 to 12 cm. The fish has an elongated and slender body, resembling an eel in shape. A distinctive characteristic is the unusually long dorsal fin, which extends almost the entire length of the back. The other fins are not large. Their coloration is predominantly dark, with shades of chocolate-brown.

Habitat

This fish species originates from regions of Southeast Asia. Its wild populations inhabit waters in Malaysia and Indonesia, particularly on the islands of Kalimantan and Sumatra. It prefers to live in small, shallow streams that flow through tropical forests. Such habitats are usually protected from direct sunlight by dense riparian vegetation and overhanging tree canopies.

Behavior and Compatibility

Representatives of this species lead a rather solitary lifestyle. During daylight hours, the Dragon Loach prefers to hide in various shelters. It actively guards its territory and chosen hiding spot from encroachments by conspecifics and other aquarium inhabitants. For this reason, it is undesirable to keep several Chocolate Loaches or other bottom-dwelling fish in a small aquarium. This species coexists well with many non-aggressive fish of comparable size that inhabit the water column or surface.

Care and Maintenance

The aquarium volume for keeping one or more loaches should start from 80–100 L. The decor must include shelters for each Chocolate Loach, such as caves or grottoes formed from driftwood and rock piles. A soft sandy substrate, covered with a layer of leaves, will be an ideal solution. Leaves will not only create a natural look but also enrich the water with tannins, which is characteristic of this species' natural habitat. Lighting should be subdued. Therefore, when choosing plants, preference should be given to shade-loving species such as Anubias, Cryptocorynes, as well as aquatic mosses and ferns. For long-term keeping, gentle filtration must be provided. The fish are sensitive to strong currents. It is important to ensure that the loach cannot accidentally enter the filter system's outlets in search of shelter. In their natural environment, their diet consists of small invertebrates they find in the substrate layer. In aquarium conditions, they can be accustomed to dry foods in the form of flakes and granules, but these should only serve as a supplement to the main diet, which consists of live or frozen foods such as Artemia, bloodworms, Daphnia, as well as pieces of shrimp meat and the like.

Diet

In nature, the diet of these fish consists of small invertebrates they forage from the substrate. In home aquariums, they can be successfully accustomed to dry foods in the form of flakes and granules. However, such foods should only be a supplement to the main diet, which should consist of live or frozen products. These may include Artemia, bloodworms, Daphnia, as well as pieces of shrimp meat and other similar foods.

Breeding and Reproduction

The species has not been bred in aquaria, and almost nothing is known about its reproduction in the wild either. Adult females are probably noticeably thicker-bodied and larger than males; no other external differences have been reported. The fish is hard to collect in its habitats, so it appears in the trade irregularly and only as wild-caught stock.

Diseases

No specific diseases have been described for this species. The main health risk factor is a violation of keeping conditions, particularly the use of an unsuitable substrate. Keeping them on coarse or sharp substrate leads to skin damage, which increases the likelihood of bacterial infections. For prevention, it is recommended to use fine, soft sand and maintain water cleanliness, avoiding the accumulation of organic waste.

How to choose

When purchasing a Dragon Loach, special care should be taken, as this species is rare and often sold in a weakened state after transport. It is important to carefully inspect the fish for signs of emaciation, skin or fin damage, which may indicate stress or the development of bacterial infections. A healthy specimen should be active (in the evening), have clear eyes, and no visible ulcers or spots on the body. Given the species' reclusive lifestyle, fish in stores often hide in decorations, so before purchasing, it is recommended to ask the seller to carefully catch them for visual inspection. Avoid buying individuals that appear apathetic, constantly lie on their side, or show signs of rapid breathing. Since the Dragon Loach is sensitive to water quality, it is crucial to inquire about its keeping conditions in the store and ensure that the fish has undergone an adaptation period after import.

Compatibility

There are no pair reviews for this species yet — check tankmates in the matcher.

All tankmates

Plants and this fish

Matching water does not mean the plant will stay intact.

Frequently asked questions

The essentials: size, tank volume, water parameters and care

How big does Dragon Loach get?

An adult reaches 12 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.

What size aquarium does Dragon Loach need?

The recommended volume is 108 L. A smaller tank speeds up nitrate build-up and raises stress levels.

What water parameters does Dragon Loach need?

Temperature 23–29 °C, pH 3.5–7.5, hardness 0–12 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.

How long does Dragon Loach live?

Around 5 years when kept properly. Lifespan depends directly on tank volume, water quality and a varied diet.

Is Dragon Loach aggressive?

Temperament: territorial (often aggressive). Keep this in mind when choosing tank mates.

How many Dragon Loach should be kept together?

Recommended setup: solitary. Ignoring this is a common cause of stress and disease.

What does Dragon Loach eat?

Diet type: mixed diet (meat + plant-based). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.

What is the scientific name of Dragon Loach?

The scientific name of the species is Vaillantella maassi, family Vaillantellidae.

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Other scientific names and conservation status

Categories
Loaches
Conservation status
Least concernLC