Black Ruby Barb (Purple-Headed Barb) Fish Species Profile

Characteristics, Origin, and Helpful Information for Hobbyists

Puntius nigrofasciatus - Black Ruby Barb

The black ruby barb is a peaceful, beautiful small barb from the forested streams of Sri Lanka, off the southern coast of India. Best described as a friendly omnivorous tank mate, it may have issues with being out-competed by larger, more carnivorous fish. In the wild, both deforestation and over-collection have put this species at risk.

Species Overview

COMMON NAMES: Purple-headed barb, purplehead barb, ruby barb, black barb

SCIENTIFIC NAME: Pethia nigrofasciata

ADULT SIZE:  2 inches



Family Cyprinidae
Origin Sri Lanka
Social Peaceful
Tank Level Bottom
Minimum Tank Size 30 gallon
Diet Filamentous algae and detritus
Breeding Egg-scatterer
Care Easy
pH 6.0 to 6.5
Hardness 5 to 12 dGH
Temperature 72 to 79 F (22 to 26 C)

Origin and Distribution

The ruby barb originates in Sri Lanka, where it was once plentiful in the forest streams in the upper elevations of the Kelani and Niwala river basins. This native habitat is composed of dense vegetation and slow-moving waters, which are colder than many tropical areas. The water in these streams is soft and acidic, and the river beds are composed of sand or fine gravel. 

Unfortunately, populations have greatly diminished due to over-catching by those selling these fish for export in the aquarium trade. Rapid deforestation has also eliminated much of the original habitat of these beautiful fish. At one point, they were on the brink of extinction but are currently listed as vulnerable by the International Union for Conservation of Nature (IUCN). Only with proper conservation methods will they remain as a viable population in the wild.

As of 2020, the export of wild-caught ruby barbs from Sri Lanka is prohibited. All specimens sold in the aquarium trade are commercially bred, either in Sri Lanka or in a number of other countries that commercially breed aquarium fish. This commercial breeding has resulted in the creation of a variety of new colors and fin morphs compared with the wild fish.

Colors and Markings

Possessing a pointed head, high back, and deep body, the ruby barb is similar in body type to other banded barbs, such as the tiger barb. Three wide black bands run vertically through the body. In juvenile fish, the body is a pale yellow to yellow-gray. As the fish matures, the head becomes purple-red in color. In males, the entire body assumes this deep red color once they attain breeding age.

Both sexes will pale in color when they are stressed, frightened, or are suffering from a disease or poor care. It is quite common for specimens in pet shops to appear washed out, then regain their bright coloration when taken to a quieter environment in a home aquarium. This species does not have barbels, which are feelers near the mouth or nasal cavity, like other barbs.


Ruby barbs are schooling fish that should always be kept in groups of eight or more. They are less nippy than the tiger barb and are suitable for community aquariums with other peaceful fish. Tetras, other barbs, danios, catfish, and gouramis can generally be safely kept with ruby barbs. Livebearers are also suitable tank mates. Ruby barbs make a nice visual contrast with schools of other vertically striped barbs, such as tiger barbs.

Black Ruby Barb Habitat and Care

In the wild, the ruby barb lives in the cooler slow-moving forest streams that are shaded by heavy vegetation. The water is soft and acidic, and the stream bottom is sandy with a layer of mulm (organic detritus). Replicating these conditions in the aquarium is ideal.

Keep the water temperature in the 72 to 79 degree Fahrenheit range and use floating plants to subdue the lighting. Use sand or small gravel for the substrate, preferably in darker colors. A live-planted tank is ideal, although artificial plants will also suffice. Open space for swimming should be provided, as well as plenty of hiding places. Ruby barbs will become pale in color, and skittish if there are no hiding places to make them feel comfortable.

Black Ruby Barb Diet and Feeding

Ruby barbs are benthic feeders or bottom feeders. They rummage for bits of organic material in the detritus that builds-up on the bottom of the forest streams they live in. Their diet is almost entirely composed of this detritus and algae.

For this reason, it’s important to keep plenty of vegetable matter in their diet. Flake foods high in vegetable matter, or vegetables such as shelled peas, pieces of raw zucchini, and blanched lettuce or spinach, are all good choices.

You can augment their primarily vegetarian diet with occasional feedings of live foods. Bloodworms, daphnia, and brine shrimp are all good choices to feed as a supplement every week or two.

Gender Differences

Adults will grow to a bit over two inches in length, with the males being slightly larger overall than females. The entire dorsal fin will become deep black in males, while only the base of the dorsal fin becomes dark in females. Likewise, in males, the pelvic and anal fins will be black or red-black. In females, these fins will be far paler in color.

As with many species, the male ruby barb gets more brilliantly colored than the female, particularly during the spawning season. The female does not undergo a significant color change when spawning, and the females have a rounder belly.

Breeding the Black Ruby Barb 

Ruby barbs are egg-scatterers that may be bred in pairs or in groups. This species readily eats its own eggs and must be removed from the spawning tank once the eggs have been laid and fertilized. The water in the spawning tank should be soft, acidic, and from 77 to 82 degrees Fahrenheit. Fine-leafed plants like java moss or spawning mops should be provided for the fish to scatter their eggs upon. Lighting should be very dim.

Breeding pairs or groups should be conditioned with plenty of small live foods in addition to their vegetation. Frozen bloodworms and brine shrimp may be substituted if live food is not available. The male will develop intense deep ruby coloration throughout the entire body. The female will not change color; however, she will become plump as she fills with eggs.

Spawning begins with the male spreading his fins and swimming around the female in a courtship display. The process may take several hours from start to finish and produce as many as 100 eggs. Once spawning is complete, the adult fish should be promptly removed from the tank. Shield the tank from light, as the eggs and fry are sensitive to light. 

The eggs will hatch in approximately 24 hours, and the fry will become free swimming in another 24 hours. Initially, the fry will consume infusoria or commercially prepared fine fry food. Within a few days, they may be fed freshly hatched brine shrimp. If the eggs fail to hatch, make sure the spawning pair are well conditioned with high-quality foods before the next spawning. It is believed that an inadequate diet is responsible for many spawning failures.

More Pet Fish Species and Further Research

If ruby barbs appeal to you, and you are interested in some compatible fish for your aquarium, read up on:

Check out additional fish species profiles for more information on other freshwater fish.