The "Black Ruby Barb", "Pethia” nigrofasciata, is a hardy fish suitable for a community aquarium as long as some care is exercised in the selection of the other fish.
Other common names for fish are "Purple Headed Barb" and “Ruby Barb". Other Scientific names that have been used are Puntius nigrofasciatus and Barbus nigrofasciatus. These other scientific names are both valid synonyms.
The "Black Ruby Barb comes from Asia like many barbs. It is restricted to forest streams in Sri Lanka (formerly Ceylon) and come from hilly areas up to about 1000 feet above sea level. Although Sri Lanka is very close to the equator, these hill streams are well shaded and tend to be reasonably cool.
This fish is not native to any other country, but has been introduced to Colombia.
Length and Longevity
It grows to about two and a half inches (7 cm) long. They can live up to 5 years in an aquarium.
The Black Ruby Barb prefers reasonably soft, slightly acidic water with a pH of between 6.0 and 6.5. I find that the captive bred ones can be adapted to neutral water (pH 7). I have never kept any wild caught ones, but they may be more sensitive to the water chemistry. Its ideal temperature range is 20-27 degrees C (68-81 degrees F). It will take a little higher for short periods.
In the wild it schools in slow flowing streams and rivers with abundant vegetation. Their aquariums should be very well planted with some free space for swimming.
The Black Ruby Barb does not like dirty water with a lot of fish wastes and regular partial water changes are a good idea. It is also one of the fish more susceptible to "Ich" (White Spot). You need to watch out for this disease and be ready to treat for it.
The Black Ruby Barb is an omnivore adapted to eat a lot of vegetable matter. It will eat any normal fish food, but live food is preferred and if possible some mosquito larvae, blood worms, Daphnia or other suitable sized live food should be given. Frozen Blood worms are also good and may be easier to obtain and store than live food.
However, although these foods greatly benefit this fish in moderation, in the wild its diet has a large proportion of vegetable matter including filamentous algae, so do not overdo the meaty foods.
Black Ruby Barbs are schooling fish and should be kept in schools of at least six fish. Although not the most aggressive fish kept in aquaria, they can nip the fins of slow moving fish. I would avoid putting it with long finned fish like Siamese Fighting Fish, Guppies and Endlers Guppies.
Some suitable companions for a school of Black Ruby Barbs are Gold Barbs, Pristella Tetras, Rummy Nose Tetras, Harlequin Rasboras, Scissortail Rasboras, Lemon Tetras, Black Widow Tetras, Emperor Tetras, Head and Tail Light Tetras, Glass Bloodfin Tetras, Swordtails, Platies, Zebra Danios, Glowlight Tetras, Australian and New Guinea Rainbowfish and White Cloud Mountain Minnows as well as the Corydoras catfish like the Peppered Catfish.
I would not recommend them as companions for Mollies, Neon Tetras and Cardinal Tetras. The reason I do not recommend them for aquariums with Mollies is the big differences in water requirements.
Also avoid large and predatory fish with Black Ruby Barbs.
The Male Black Ruby Barb changes colour when it is ready to breed. In this state, it becomes clear why it is called things like the Purple Headed Barb. The males get an intense red- black colour. They tend to be a bit bigger than the females. The females are a little plumper than the males.
In the wild the Black Ruby Barb spawns near the edges of the steam or pool it lives in among the plants growing in the shallow water. People who live in a suitable climate could set up a suitable pond and breed these fish in a nearly natural way.
The Black Ruby Barb is an egg scatterer, and lays its eggs over plants, preferably fine leaved ones. The water for spawning should be soft and moderately acidic with a temperature of about 27 C (80 F). Typically they will spawn first thing in the morning.
About 400 eggs per female should be laid. By using marbles on the bottom of the tank, most of the eggs should fall out of reach of the parents. As with many fish, Black Ruby Barbs eat their own eggs and babies. It is usual to remove the parents after spawning.
Keep the eggs dark until they hatch. The eggs hatch in about one day, and are free swimming after about a week.
The babies will eat protozoa (infusoria) at first and this can be supplemented with the finest fry foods. As they grow, the babies can be fed bigger fry food and will be helped to grow by suitable sized live food like screened Daphnia.
The IUCN Red List of threatened species considers this fish as being of lower risk of extinction, but that its survival depends on conservation. The export of Black Ruby Barbs from Sri Lanka is illegal and all the ones you can buy in aquarium shops should be captive bred. Some illegal catching of this fish does occur. There is some evidence that in certain populations the selective catching of more brightly coloured fish is causing the population to become less colourful overall.
The shady mountain streams this fish comes from are being so degraded by people that there is very little of the habitat that this fish thrives in left, and this is seriously threatening the fish’s survival in the wild.
Hybridizing between two different species of fish is something frequently strongly disapproved of by serious aquarists; there are some people who do it. Black Ruby Barbs can produce hybrids when crossed with Puntius stoliczkanus, the Tic-tac-toe Barb, with Puntius cumingii, Cuming's Barb, and with Puntius tetrazona, the Tiger Barb.
As with all captive fish, do not allow them to get out into ecosystems they are not native to.