All About Denison Barbs: An Exquisite Tropical Fish

The Denison Barb, also known as the Red Lined Torpedo Barb or Roseline Shark, is a popular and attractive fish species in the aquarium hobby. Denison barb (lat. Sahyadria denisonii) is one of the fishes that are getting popular with surprisingly high rate. The fish has become a subject of aquarists focus quite recently. This India-born fish has become rather renowned species due to its appealing look and interesting behavior.

Habitat in the wild

The Denison barb was called by the name of Sir William Thomas Denison (1804—1871), a governor of Madras city, India (since 1861 till 1866). Denison Barbs are endemic to the southwestern region of India, specifically the rivers of the Western Ghats mountain range (endemic species of Achenkovil, Pamba and Chaliyar rivers). They are found in the states of Karnataka and Kerala. On India home market this kind of fish is called «Miss Kerala» and «Chorai Kanni» (which literally means ‘bleeding eyes’).

Denison Barbs inhabit clear, fast-flowing rivers and streams characterized by rocky substrates and a moderate current. They are commonly found in areas with dense vegetation along the riverbanks. The rivers where Denison Barbs reside are often lined with dense vegetation, including aquatic plants, submerged roots, and overhanging vegetation. These plants provide them with cover and hiding spots, as well as areas to forage for food.

Though this fish kind was described a while ago, it has become popular quite recently (approximately since 1997). This is due to the fact that breeding this fish in captivity is quite a challenging task which in its turn stipulates its high price.

Sadly, this fish can be used as an example of the situation when the fish suddenly becomes highly demanded on the market. Since it was acknowledged as the best one on the international exhibition of aquarium husbandry, the demand on the market has increased fast. As a result of fishing this species to sale them as well as because of rivers contamination with agricultural and household wastes (detergents, fertilizers and ect.) the natural population of the species has decreased by 50 % for the last 15 years.

Government of India has taken actions in this respect: prohibition of fishing and exporting of Denison barb as well as this fish kind is now taken under protection of National Wildlife Protection Act. The International Union for Conservation of Nature (IUCN) has assessed the conservation status of the Denison Barb as Endangered.

Efforts have been made to conserve and protect the Denison Barb in its native range. Conservation organizations and government bodies in India have been working towards the sustainable management of aquatic ecosystems and the protection of endangered species. These initiatives involve habitat restoration, regulation of fishing practices, and raising awareness about the conservation needs of the species.

Description

The overall body coloration of the Denison Barb is silver or light gold. One of the most distinctive features of the Denison Barb is the presence of prominent horizontal red or orange stripes that run along the length of its body. These stripes start from the head and extend all the way to the tail. The number and intensity of the stripes may vary among individuals.

In addition to the vibrant body stripes, the fins of the Denison Barb are also colorful. The dorsal fin, caudal fin (tail fin), and anal fin usually exhibit shades of red or orange. The fish has black and yellow stripes on its claw-ended tail fin. First rays of the dorsal are also bright red and the rest of its fins are transparent.

How big do denison barbs get?

The body of the Denison Barb is elongated and torpedo-shaped, with a streamlined profile. It typically grows to a length of 4-6 inches (10-15 cm) when fully mature, but as a rule it is a bit smaller about 9–11 centimeters (3.5–4.3 in).

The average lifespan of Denison Barbs (Sahyadria denisonii) in captivity is around 5-7 years. However, with proper care and optimal conditions, some individuals have been reported to live even longer.

Characteristic	Description
Scientific Name	Sahyadria denisonii
Common Names	Denison Barb, Red Lined Torpedo Barb, Rose Line Shark
Native Range	Rivers of the Western Ghats, India
Conservation Status	Endangered
Size	Up to 4-6 inches (10-15 cm) in length
Lifespan	Approximately 5-7 years in captivity
Appearance	Sleek, torpedo-shaped body with silver/gold body color; Prominent horizontal red/orange stripes along the body; Red/orange fins for added visual appeal
Temperament	Generally peaceful, but can show aggression towards fin-nippers or slow-moving fish with long fins
Preferred Habitat	Fast-flowing rivers and streams with rocky substrates
Water Parameters	Temperature: 72-79°F (22-26°C); pH: 6.5-7.5; Hardness: 5-15 dGH
Diet	Omnivorous, consuming a variety of foods including small invertebrates, insect larvae, algae, and plant matter
Recommended Tank Size	Minimum of 40 gallons (150 liters) for a small group
Schooling Behavior	Should be kept in groups of at least six individuals to promote natural social behavior
Compatibility	Compatible with other active and similarly sized fish species, such as other barbs, danios, or rasboras
Breeding Behavior	Egg scatterers, requiring specific conditions for spawning such as slightly acidic water, higher temperatures, and fine-leaved plants for egg deposition

Difficulties in keeping

Keeping in a tank my be quite challenging. In the wild the Denison barb dwells in fast and clean rivers, so in a tank it requires oxygen-rich water, very low nitrates and ammonia level and fast water flow.

Besides, breeding is complicated and not studied enough yet. This is a peaceful and schooling fish. If you keep it alone, it becomes very timid, so it’s better to keep a school of at least 6 species.

The Denison barb is quite large (if compared to other barb species), active and brightly colored one. It inhabits in India, but the uncontrolled fishing-out of this fish for several years has led to the situation that now barb is danger of extinction. India government introduced limitations on fishing this species in the wild and currently barb is bred in the fish farms or caught in the wild by small groups of poachers.

Care and keeping in a tank

Tank size

Recommended tank volume is 200 liters (44 gallons) and more. Since this is a schooling fish, it’s better to keep barb in a group of 5-7 species. Maintaining proper number of Denison barb species in a group will ensure maximum brightness of the fish natural coloring as well as the fish will be less prone to timidity.

Any demonstration of aggression within the school as a rule shows that they are trying to build hierarchy in the group. Once they define the leader, they start living friendly and peacefully.

Tank decor

In the wild Denison barb dwells in fast flowing rives and streams with oxygen-rich water. If you want to create tank conditions similar to ones the fish has in its habitat, it is better to keep them in a tank with constant water flow.

You can use sand or gravels as the tank bottom substrate as well as put some smooth stones of various size around the tank perimeter. An external filter will provide required high level of oxygenation and water flow.

Also it is desirable to cover the tank tightly. The fish is active and fast, so it can easily jump out of the tank. You may put some additional decorations into the tank – snags, water plants with strong roots. You may use fern, Java moss, plants of Bolbitis and Anubias kind.

Denison barbs may lose a bit of their bright coloring when they are put into a new tank or if the tank doesn’t have enough of decorations. This happens due to stress, change of tank water composition and getting new tank mates

Water parameters

Special attention should be paid to the tank water quality, because in the wild this kind of barb inhabits in fast flowing waters and usually the level of organic contamination is very low there. That’s why you have to keep strict watch on the tank cleanness.

Optimal water parameters:

1. Temperature: The ideal temperature range for Denison Barbs is between 72°F and 79°F (22°C to 26°C).
2. pH Level: Denison Barbs prefer slightly acidic to neutral water conditions. The recommended pH range is between 6.5 and 7.5. It’s essential to monitor and maintain a stable pH level in the aquarium.
3. Water Hardness: Denison Barbs can adapt to a moderate range of water hardness. The recommended hardness level, measured in degrees of General Hardness (dGH), is between 5 and 15 dGH.
4. Ammonia, Nitrite, and Nitrate: Denison Barbs are sensitive to ammonia and nitrite levels, so it’s crucial to ensure that these parameters are kept at zero or undetectable levels. Regular water testing and proper filtration are essential to maintain good water quality. Additionally, it’s important to keep nitrate levels as low as possible, ideally below 20 ppm.
5. Water Filtration and Flow: Denison Barbs are accustomed to fast-flowing rivers in their natural habitat. It’s beneficial to provide a moderate to strong water flow in the aquarium to simulate their natural environment. A good filtration system, along with regular maintenance, is necessary to keep the water clean and well-oxygenated.

Diet

The Denison barb is an omnivorous one. In the wild they feed mainly on insects and other spineless as well as they eat plant food (algae, for example). In a tank barbs will eat almost everything you give; all types of natural and artificial food.

To ensure that the fish is healthy and shows its best coloring you should feed it with live and frozen food, such as bloodworm, daphnia, brine shrimp as well as with dry food – flakes and pellets. Right after getting the fish, it is better to feed denison barb with flakes rich in astaxanthin and carotinoids to restore the coloring that may get paler due to stress cause by transportation.

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Tank mates

Denison Barbs are generally peaceful fish, but they can display some aggression towards smaller, slower-moving fish with long fins. When selecting tank mates for Denison Barbs, it’s important to consider their active nature and their potential to nip at the fins of certain species. Keeping Denison Barbs in a small group of six or more individuals is highly recommended. They are shoaling fish and thrive when kept with their own species.

Denison Barbs are often kept in groups with other barb species such as Cherry Barbs (Puntius titteya), Tiger Barbs (Puntigrus tetrazona), or Odessa Barbs (Puntius padamya). It’s important to provide adequate swimming space and maintain a large enough group of each species to spread out aggression.

Zebra Danios (Danio rerio) and Pearl Danios (Danio albolineatus) are active and fast-swimming fish that can be suitable tank mates for Denison Barbs. They are compatible in terms of water parameters and behavior.

Harlequin Rasboras (Trigonostigma heteromorpha) and Lambchop Rasboras (Trigonostigma espei) are peaceful shoaling fish that can coexist well with Denison Barbs. They share similar water parameter requirements and make good companions.

Peaceful tetra species like Black Neon Tetras (Hyphessobrycon herbertaxelrodi) or Ember Tetras (Hyphessobrycon amandae) can be compatible with Denison Barbs. However, it’s important to avoid tetra species with long, flowing fins, as they may become targets for nipping.

When introducing any new fish to the tank, it’s recommended to observe their interactions closely. In case of aggression or compatibility issues, it may be necessary to rearrange tank decorations or make adjustments to the tank mates.

Here are some examples of tank mates that may not be suitable:

1. Slow-moving or Long-finned Fish: Denison Barbs can be fin nippers, particularly if they perceive long fins as potential targets. Avoid keeping them with fish like Fancy Guppies, Angelfish, or Siamese Fighting Fish (Betta splendens), as they may become victims of aggression.
2. Aggressive or Territorial Fish: Avoid combining Denison Barbs with aggressive or territorial species that may instigate conflicts or dominate the aquarium. This includes fish like Red-tailed Sharks.

Gender differences: male vs female

There is no stark difference between the Denison barb male and female. It is quite difficult to define gender differences of the fish.

However, there are some subtle differences that can help in determining the sex of adult Denison Barbs:

1. Body Shape: Males tend to have a more slender and streamlined body shape compared to females. Females, especially when mature and ready to spawn, may have a slightly rounder and fuller body shape.
2. Size: In some cases, males can be slightly smaller and more slender than females, but this is not always a reliable indicator as there can be individual variations.
3. Coloration: While both males and females exhibit the characteristic horizontal red or orange stripes along their body, some individuals claim that the color intensity of the stripes might be more pronounced in males. However, this is not a definitive indicator and can vary among individuals.
4. Behavior: During breeding or spawning periods, males may display more vibrant coloration and become more territorial and aggressive. They may also exhibit courtship behavior, such as chasing females or performing display dances.

If you are interested in breeding Denison Barbs, it is advisable to acquire a group of juveniles and allow them to grow and mature. As they reach sexual maturity, their physical and behavioral differences may become more apparent.

Breeding

There are no precise recommendations on how to breed in home aquaria. There were just some isolated incidents of obtaining barb offspring. As for the fish you see on sale, they are most likely to be bred by means of hormonal injections.

Several years ago when Denison barb came to Europe and created a furor all over the world, there was very little information about peculiarities of their breeding. At that time denison barb costed quite expensive 50-150 euros for one fish.

As the years went by some more information was obtained in this respect. In Germany several successful attempts of this barb breeding were performed. In their case the group of 15 adult species spawned successfully in soft, acidic water (GH 2-3/ pH 6,0), they scattered their eggs on a bunch of java moss.

The spawning was triggered by gradual decrease of tank water pH by means of adding pieces of peat into the tank. Chester Zoo Tank in England reported about successful breeding. This happened accidentally, though the Zoo has obtained the second spawning in more controlled conditions.

Their theory is that Denison barb requires a bigger group for spawning – as a the result the fish will spawn massively.