Sheatfishes (Siluridae)

Glass Catfish Twin

Kryptopterus geminus

Kryptopterus geminus, known as the Glass Catfish Twin, is a representative of the family Siluridae (Catfishes). Its name "twin" is due to its close relationship with another, quite popular species – the Ghost Glass Catfish. Interestingly, these two species were formerly considered one. In retail stores, they are often confused, but this error does not lead to problems, as their keeping requirements are similar.

Tank
from 250 L (66 gal)
Temperature
20 – 28 °C (68 – 82 °F)
Size in aquarium
17 cm (6.7 in)
Acidity
pH 6–7.5

Dangerous to small fish

Natural rangeRange on the map
  • Mekong River Basin
  • Cambodia
  • Laos
  • Thailand
  • Vietnam

Tank conditions

Plan the tank stocking
Temperature
20 – 28 °C (68 – 82 °F)
Water pH
Slightly acidic (6) – Neutral (7.5)
Water dH
Very soft (2) – Hard (15)
Water salinity
no salt (freshwater)
Size in aquarium
17 cm (6.7 in)
Lifespan
5 years
Temperament
Semi-peaceful dangerous to smaller ones
Toward small fish
a risk to small fish
Required aquarium volume
from 250 L (66 gal)
Lighting
dimmed
Substrate
any (no restrictions)
Water flow
weak or moderate
Swimming level
middle level
Feeding
Any (universal)
Keeping
Small group 3–4 individuals
Jumping
low
  • 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 (small group (3–4 individuals)), footprint, decor and tank mates.

Care and keeping

Description

These individuals can reach up to 17 cm in length. The appearance of the Glass Catfish Twin almost completely matches that of the Ghost Glass Catfish, from which it differs only in some morphological details: it is slightly larger, has a narrower head, and an elongated anal fin. Sexual dimorphism is weakly expressed, making it difficult to distinguish males from females.

Habitat

The natural habitat of this fish covers the lower and middle basins of the Mekong River in Southeast Asia, including territories of Thailand, Laos, Cambodia, and Vietnam. It prefers the murky waters of large tributaries and small streams.

Behavior and Compatibility

This catfish is distinguished by its peaceful and calm disposition. It is quite capable of coexisting with other species of similar size. However, it is advisable to avoid overly active or large fish that may compete for food. It is also important to consider that overly small fish or fry can sometimes become accidental prey.

Care and Maintenance

For a group of 4–5 fish, an aquarium of 250–300 liters or more is desirable. The choice of decor is not critical; the main thing is to provide subdued lighting and create enough hiding places. These can include dense plant thickets, piles of snags, or other decorative elements. The long-term well-being of the Glass Catfish Twin depends on maintaining stable water conditions within acceptable temperatures and hydrochemical parameters. For this, it is necessary to equip the aquarium with all the required equipment and regularly perform essential care procedures. In particular, 20–30% of the water volume should be replaced with fresh water weekly, and organic waste should be removed promptly.

Diet

In natural conditions, the diet of this fish consists of invertebrates, crustaceans, and other zooplankton, as well as smaller fish. For successful keeping in a home aquarium, a varied diet including dry, frozen, and live foods should be offered.

Breeding and Reproduction

Information on the successful breeding of this species in artificial conditions is absent. In the natural environment, spawning is associated with the change of dry and wet seasons. With the onset of rains, the catfishes migrate to flooded areas of tropical forests for spawning, where the emerging fry are relatively safe and provided with an abundance of food.

Diseases

Most health problems in fish often arise from unsuitable keeping conditions. Maintaining a stable and comfortable habitat is a key factor for successful keeping. If symptoms of illness appear, the first step is to check the water quality. If deviations are found, it is important to take immediate measures to eliminate them. If the symptoms do not disappear or worsen, medicinal treatment may be required.

How to choose

When selecting individuals in a store, pay attention to body transparency: in healthy fish, it should be clear, without cloudy spots, film, or hemorrhages. Avoid specimens with damaged fins or signs of emaciation, where skeletal bones are prominent. Since this species is schooling, acquire a group of 4–5 fish at once, as solitary keeping causes them severe stress. In the store, observe their behavior: healthy catfishes stay in the water column, show activity, and react to movement from outside. Lethargic fish that constantly lie on the bottom or try to hide in the corner of the aquarium may be weakened or sick. Make sure there are no aggressive species in the aquarium with them that could cause injuries, as injured fish adapt extremely poorly to new conditions.

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 Glass Catfish Twin get?

An adult reaches 17 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.

What size aquarium does Glass Catfish Twin need?

The recommended volume is 250 L. A smaller tank speeds up nitrate build-up and raises stress levels.

What water parameters does Glass Catfish Twin need?

Temperature 20–28 °C, pH 6–7.5, hardness 2–15 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.

How long does Glass Catfish Twin live?

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

Is Glass Catfish Twin aggressive?

Temperament: semi-peaceful (dangerous to smaller ones). Not a predatory species, but small fish that fit in its mouth will eventually be eaten.

How many Glass Catfish Twin should be kept together?

Recommended setup: small group (3–4 individuals). Ignoring this is a common cause of stress and disease.

What does Glass Catfish Twin eat?

Diet type: any (universal). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.

What is the scientific name of Glass Catfish Twin?

The scientific name of the species is Kryptopterus geminus, family Sheatfishes (Siluridae).

Similar fishes

Matched by family, categories and overlapping keeping conditions

Two-barbel Glass Catfish

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Spotted Glass Catfish

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Other scientific names and conservation status

Categories
Catfish
Conservation status
Least concernLC