The Black-bar Chromis, both gorgeous and durable, makes a terrific saltwater aquarium fish!
The Black-bar Chromis Chromis retrofasciata has a very delicate balance of color. A pronounced horizontal black stripe over it’s posterior is set against a yellowish to tan body. Juveniles sport a subtle touch of neon blue encircling the eye and etched along the bottom fins and the underside of the tail.
There are few fish it can be confused with. Other damsels may have the same coloring, but always lack the vertical black bar at the back of the body. Other common names they are known by include Black Back Chromis and Blackbar chromis, and in Australia they are called a Blackbar Puller.
This diminutive fish reaches only just about 2 inches (6 cm) in length. It is one of the few Chromis that are found alone in the wild. Many other Chromis species like to form very large schools, yet this species is happy alone or with just 2 or 3 friends to hang out with. The same is true in captivity. Chromis do not form bonded pairs and several males and females will breed with other males and females. Males will guard the nest until the eggs hatch.
Along with its nice coloring it has a nice personality and is inexpensive. Though designated as a true damselfish, they are not very aggressive, and so make a great choice for most tanks. Unlike other genera in the damselfish family, Chromis are better tempered and tend to be the ones that are picked on. Though they are not overly aggressive, they can get testy in cramped quarters, even with their own kind.
They are moderately easy to keep, making them a great choice for both the beginner saltwater hobbyist and the more advanced marine aquarium enthusiast. The minimum tank size is 20 gallons (76 liters), however if keeping with other fish, provide at least 40 to 55 gallons with lots of hiding places within the live rock. Provide good water quality, proper tank mates, and several feedings a day of quality foods to ensure a long life. Having many places to hide also will help them adjust to captive life. Juveniles adjust easier than adults.
If keeping them in a nano tank, they should probably be the only fish. Adding semi-aggressive fish such as a dottyback will result in a dead Chromis; conversely adding a small goby may result in a dead goby. To keep your Blackbar Chromis with other fish, put them in a larger tank. Now your options open up. They can tolerate semi-aggressive fish if they have places to hide, but don’t house them with aggressive or larger fish that can swallow them whole.
For more Information on keeping saltwater fish see:
Marine Aquarium Basics: Guide to a Healthy Saltwater Aquarium
- Kingdom: Animalia
- Phylum: Chordata
- Class: Actinopterygii
- Order: Perciformes
- Family: Pomacentridae
- Genus: Chromis
- Species: retrofasciata
- Aquarist Experience Level: Beginner
- Aquarium Hardiness: Moderately hardy
- Minimum Tank Size: 20 gal (76 L)
- Size of fish – inches: 2.4 inches (5.99 cm)
- Temperament: Semi-aggressive
- Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
- Range ph: 8.1-8.4
- Diet Type: Omnivore
- My Aquarium – Enter your aquarium to see if this fish is compatible!
Habitat: Distribution / Background
The Black Bar Chromis Chromis retrofasciata was described by Weber in 1913. They are found in the Indo-Australian Archipelago including Indonesia, Palau, Philippines, New Guinea, New Britain, Fiji Islands and the northern Great Barrier Reef. Newer sightings have occurred in Tonga.This species is not listed on the IUCN Red List of Threatened Species. Other common names they are know by include Black Back Chromis and Blackbar chromis, but in Australia they are called a Blackbar Puller.
This species is a member of the very large Pomacentridae family of Damselfish and Anemonefish. It belongs to the subfamily Chrominae in the Chromis genus, which is the largest group of fish in the family. There are currently 100 recognized species in this genus, though only a few are collected for the aquarium trade.
The Chromis species are more streamlined than others in the family, and have a deeply forked tail. This tail fin provides them with the ability to swim fast and furious with their shoal or away from predators. The Chromis also have orbital papillae, small rounded protuberances on the back and bottom edges of the eye’s orbit. This is found on other zooplanktivores as well, such as anthias, and is thought to help reduce turbulence as they swim.
Chromis are one of the less aggressive damselfish. Because of this they will get along well with other individuals of the same species as well as with other species of fish, corals and invertebrates. They are about as hardy as their close relatives, but are more of a schooling fish. Many species feed mostly on planktonic crustaceans in the water column, but can exhibit seasonal changes to their diet, feeding heavily on filamentous and floating algae as well.
The Blackbar Chromis inhabit waters as shallow as 10 feet and as deep as 213 feet (3 – 65 m). They are typically found in outer reef faces, lagoon patch reefs and fringing coastal reefs. The water is generally clear with dense stony coral growth.
They can be found singly or sometimes in small groups, but stay close to the shelter of the thick branching corals. Blackbar Chromis consume benthic weeds and algae, as well as zooplankton and other planktonic invertebrates.
- Scientific Name: Chromis retrofasciata
- Social Grouping: Varies – Typically solitary, but will also be found in small schools.
- IUCN Red List: NE – Not Evaluated or not listed
The Black Bar Chromis is compact and slightly deep bodied. They can reach up to 2.36 inches (6 cm) in length, though typically only grow to about 2 inches. Males and females are the same size. In the wild they live from 2 to 7 years, but in captivity can live up to 20 years.
Their name is descriptive of the black vertical bar, which is just in front of the tail fin area, running the entire height of the fish. The body color can range from yellow or tan to pale yellow or yellowish brown. They have a dusky brown forehead and black eyes, rimmed with a thin white ring along the bottom edge. The pectoral fins are yellow and the pelvic fins are white. Both the dorsal and anal fins are yellow but become opaque or clear at the exterior. The tail is white at the base and transparent white in the fin area.
The male’s body color changes to a muted yellow during spawning. Juveniles have accents of blue around the eyes, as well as the tips of the pelvic and anal fins. In general, the fins turn white as they age.
Although they have a rather distinct look, there are a couple of other fish that may be confused with them. One is the Malayan Chromis Chromis flavipectoralis. Though rarely seen by aquarists, this chromis lacks the black bar and dusky head, but does have the yellow body and white tail fin. Another is the Yellow Chromis Chromis analis which also lacks the black bar and has the yellow body and white tail fin.
- Size of fish – inches: 2.4 inches (5.99 cm) – They typically only grow to about 2 inches (5 cm) in length..
- Lifespan: 20 years – In the wild their life span is 2 to 7 years, but in captivity, some species may live up to 20 years.
Fish Keeping Difficulty
The Black Bar Chromis is moderately hardy and a great choice for beginner saltwater hobbyists who are dedicated to providing good water quality. It is among the easiest of all marine fish to keep, but they are more susceptible to illnesses due to poor water quality and improper tank mates when compared to others in the damselfish family. Performing normal water changes, feeding them a variety of foods several times a day, and having proper tank mates will keep your Chromis living a good long life.
These are a peaceful fish as far as damsels are concerned and can be kept with other peaceful community fish. They need at least 20 gallons, and should be kept singly in this size tank. Larger tanks can house 2 or 3, but they will fight if the tank is too small. Underfeeding will cause aggression between them.
They tend to be the fish most likely to be picked on by aggressive tank mates. Any fish that is picked on and harassed is also more likely to become sick. If they are staying in one spot in an upper corner, it is most likely due to aggression from another fish and they should be removed.
- Aquarium Hardiness: Moderately hardy – Not as hardy as other damselfish, so they need good water quality.
- Aquarist Experience Level: Beginner – They can be kept by a dedicated beginner devoted to maintaining water quality.
Foods and Feeding
The Black Bar Chromis are omnivores. In the wild, stomach contents from studies show various zooplankton, benthic weeds, and algae. In the aquarium it is best to provide variety in their diet. This can include meaty foods such as mysis shrimp, enriched brine shrimp, other finely chopped shrimp or fish, and flake for herbivores.
They will feed in the water column and at the top of the tank. If feeding pellets, make sure they are wet before adding them to the tank so air will not enter into their digestive tract, which can cause issues. It is best to feed small amounts of food several times a day. These fish eat constantly in the wild so they do better when fed at least 3 times a day.
- Diet Type: Omnivore – They lean more towards a planktivore, feeding on planktonic crustaceans in the water column, but also feed on algae.
- Flake Food: Yes – Use products with Spirulina to support their vegetable needs.
- Tablet / Pellet: Yes – Make sure the pellets are wetted down with tank water before adding to prevent air getting from trapped in their digestive tract.
- Live foods (fishes, shrimps, worms): Some of Diet – Live foods that are gut loaded are a great way to induce spawning.
- Vegetable Food: Some of Diet
- Meaty Food: Most of Diet
- Feeding Frequency: Several feedings per day – As with all planktivores, feed at least 3 times a day
These damselfish are moderately hardy and fairly easy to keep in a well maintained tank. Poor water quality will result in illness and disease with these saltwater fish. Regular water changes done bi-weekly will help replace the trace elements that the fish and corals tend to deplete. Guidelines for water changes with different types and sizes of aquariums are:
- Fish only tanks:
- Nano/Small tanks up to 40 gallons, perform 5% water changes bi-weekly.
- Medium sized up to 90 gallons, perform 15% bi-weekly.
- Large Tanks 100 gallons and over, once water is aged and stable, can be changed 10% bi-weekly to 20% monthly, depending on bioload.
- Reef tanks:
- Nano/Small tanks up to 40 gallons, perform 15% water changes bi-weekly.
- Medium sized up to 90 gallons, perform 20% to 30% monthly depending on bioload.
- Large Tanks 100 gallons and over, once water is aged and stable, can be changed 20% to 30% every 6 weeks depending on bioload.
For more information on maintaining a saltwater aquarium see: Saltwater Aquarium Basics: Maintenance. A reef tank will require specialized filtration and lighting equipment. Learn more about reef keeping see: Mini Reef Aquarium Basics.
- Water Changes: Bi-weekly – Do bi-weekly water changes of 15% in a reef setting or 20% monthly in a fish only tank.
Black Bar Chromis can be kept in either a saltwater aquarium or a mini reef. A minimum tank size of 20 gallons (76 liters) is needed for one specimen, though newer sources suggest 30 gallons. Nano tanks that are at least 20 gallons would be okay, but other tank mates should be chosen wisely. If keeping two or three, provide at least least 40 to 55 gallons with plenty of hiding places. If housing more than two to three, provide a tank that is at least 75 gallons.
Provide live rock with plenty of hiding places. Any substrate will work for these fish. Making an area of rubble with different sizes of rock to create many places to hide within will reduce aggression between them and other fish in the tank. Chromis like the upper parts of aquariums, so make sure there is plenty of open area at the top of the tank for them to swim.
Lighting and water movement are not significant factors. The water temperature should be between 72˚F to 82˚F (22 – 28˚C), with pH from 8.1 to 8.4. Similar to clownfish, optimal spawning production occurs between 79°F to 83°F (26°C to 28°C).
- Minimum Tank Size: 20 gal (76 L) – A 20 gallon tank is suggested for one specimen, although 30 gallons would be wise. An increased tank size of 40 to 55 gallons will be needed to keep 2-3, and keeping more than that will require 75 gallons and up.
- Suitable for Nano Tank: Yes – A minimum 20 gallon aquarium is fine for one fish with carefully selected tankmates..
- Live Rock Requirement: Typical Plus Hiding Places
- Substrate Type: Any – Provide an area of rubble with various sized rocks with hideouts.
- Lighting Needs: Any – It has no special lighting requirements, though if kept with live coral, they may need strong lighting.
- Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
- Breeding Temperature: 79.0° F – The optimal temperature for good quality eggs and larvae occurs with temperatures of 79° F to 82° F (26° – 28°C).
- Specific gravity: 1.023-1.025 SG
- Range ph: 8.1-8.4
- Brackish: No
- Water Movement: Any
- Water Region: Top – They will retreat to the middle areas of the tank for shelter and for sleeping.
The Black Bar Chromis are not as aggressive as other damselfish. In the wild they are typically found alone, but can be found in small groups as well. They are relatively peaceful and can be kept together with most other community fish. They do get aggressive with their own kind if the space is too confined. They do well when kept singly in a smaller tank while 2-3 will require more room in a moderate sized tank.They are a good choice for larger tanks as well, since you can keep them in groups and also have more tank mates.
If you are keeping just one do not keep it with aggressive fish, or with more boisterous semi-aggressive fish that feed on the same foods. This will cause the Blackbar Chromis to be picked on. When keeping them in a group they will do well with certain semi-aggressive fish like the more peaceful Tangs, but do not keep them with anthias or aggressive pygmy angelfish.
Larger semi-aggressive fish are okay, but only in larger tanks with the least aggressive of the fish type. For example, some triggerfish are relatively mellow like Niger Triggers, but more aggressive triggers will go after the Black Bar Chromis. The same holds true for tangs or surgeonfish. Do not house them with any large sized aggressive fish or larger fish that would swallow them whole. A Chromis staying near the top corner of a tank is an indication of it being bullied. Either remove the bully or the Chromis.
They are great in a reef tank and enjoy the safety offered by the branches of any coral you may have. They are not a threat to corals or invertebrates of any kind. They may, however, clean some algae off the bases of some large polyp stony (LPS) corals.
- Venomous: No
- Temperament: Semi-aggressive – Not very aggressive when compared to other damselfish, but is scrappy with its own kind in confined quarters.
- Compatible with:
- Same species – conspecifics: Sometimes – It will fight with conspecifics if the tank is too small. Best kept singly in minimum sized tanks, and with 2 or 3 specimens the tank will need to be at least 40-55 gallons. Any more than that will need at least 75 gallons.
- Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Monitor – Do not house these types of fish with the Blackbar Chromis in tanks under 40 gallons, due to aggression.
- Semi-Aggressive (anthias, clownfish, dwarf angels): Safe – Can be kept with clownfish in tanks that are at least 100 gallons with plenty of hiding places.
- Large Semi-Aggressive (tangs, large angels, large wrasses): Safe – If your Chromis hides all the time, you may want to remove the large semi-aggressive fish, or the Chromis.
- Large Aggressive, Predatory (lionfish, groupers, soapfish): Threat – Do not house with fish that can swallow them whole.
- Threat – These fish are too slow and delicate and peaceful to be kept with the Blackbar Chromis.
- Anemones: Safe
- Mushroom Anemones – Corallimorphs: Safe
- LPS corals: Safe
- SPS corals: Safe
- Gorgonians, Sea Fans: Safe
- Leather Corals: Safe
- Soft Corals (xenias, tree corals): Safe
- Star Polyps, Organ Pipe Coral: Safe
- Zoanthids – Button Polyps, Sea Mats: Safe
- Sponges, Tunicates: Safe
- Shrimps, Crabs, Snails: Safe
- Starfish: Safe
- Feather Dusters, Bristle Worms, Flatworms: Safe
- Clams, Scallops, Oysters: Safe
- Copepods, Amphipods, Mini Brittle Stars: Safe
Sex: Sexual differences
Males and females are the same color and size. Differences can be seen when the males change to a muted yellow color during spawning.
Breeding / Reproduction
Some of the damselfish have been bred in captivity, following the general pattern of clownfish. If breeding in captivity, note that brittle stars, serpent stars, wrasses and crabs will eat the eggs of damselfish. The eggs and larvae are much smaller than clownfish, and are difficult to rear.
Successful breeding requires perfect water parameters and a large, non-predatory aquarium system. All Chromis species are similar to clownfish, which have optimal spawns between 79°F to 83°F (26°C to 28°C). They are known to scatter their eggs over the nesting site, or what is referred to as an algae mat. These sites consist of dead coral, hard calcareous surfaces or rocks, as well as seagrass, algae, and sponges.
The male sets up his territory on the sea floor. He will show intense displays during the courtship to lure females to the nesting site that he has prepared. He will rub his genital papillae on the algal mat and the female will mimic his behavior and lay her eggs. These little eggs attach to the algal mat with small stalks. Several females will spawn with one male, and female chromis are also known to spawn with several males.
After spawning the male will then guard his nest and defend the eggs from predators. He will also keep the eggs ventilated and clean. Eggs hatch within 2 to 7 days, depending on the species and water temperature, and the larval stage lasts from 17 to 47 days. Due to similarities, see breeding techniques under Clownfish on the Marine Fish Breeding page.
- Ease of Breeding: Difficult
Chromis, which are the most delicate of all damsels, fare poorly when handled carelessly. Unlike other damsels, they are sensitive to poor water conditions, and their water needs to be monitored and tested to rule out any ammonia, nitrite or high nitrates, especially during quarantine.
Poor water quality makes Chromis very susceptible to several bacterial infections and viruses. On the positive side, they tend to be some of the first fish to show there is a problem within the tank. They also will succumb to disease if being harassed by other fish because stress inhibits their immune system. Choosing tank mates carefully can prevent stress and keep them healthy.
Damselfish are susceptible to Marine Ich Cryptocaryon irritans, also called White Spot Disease or Crypt, Marine Velvet or Velvet Disease Oodinium ocellatum (Syns: Amyloodinium ocellatum, Branchiophilus maris), and Uronema disease Uronema marinum. All of these are parasites.
The most easily cured of these is Crypt (salt water Ich), but they are all treatable if caught in a timely manner. Marine Velvet is a parasitic skin flagellate and one of the most common maladies experienced in the marine aquarium. It is fast moving and primarily infects the gills. Uronema disease, which is typically a secondary infection, is very deadly and will attack your Chromis quickly and lethally. The first symptom is lack of appetite. It is most often contracted when the aquarist lowers their salinity to treat another type of illness, but doesn’t lower it far enough. This parasite thrives in mid-level brackish water salinity, which has a specific gravity of around 1.013 to 1.020.
Treat your new Chromis as gingerly as you would an expensive saltwater fish, and they will respond well. Anything you add to your tank that has not been properly cleaned or quarantined, including live rock, corals and fish, can introduce disease. The best prevention is to take care to properly clean or quarantine anything you want to add to the tank. For information about saltwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.
The Black Bar Chromis is a seasonal item, but can be found on the internet and in stores when available. They are quite inexpensive.
- Animal-World References: Marine and Reef
- Chromis viridis (Cuvier, 1830) Blue green damselfish, Fishbase
- Pomacanthus asfur, IUNC Red List, International Union for Conservation of Nature and Natural Resources
- Scott W. Michael , Damselfishes & Anemonefishes, TFH Publications, 2008
- Scott W. Michael, Reef Aquarium Fishes: 500+ Essential-to-Know Species, Microcosm Ltd, 2006
- H. Debelius and R. H. Kuiter, World Atlas of Marine Fishes, (in German) Hollywood Import & Export, Inc., 2006
- Dr. Gerald R. Allen, Damselfishes Of The World, Aquarium Systems, 1991
- Burgess, Axelrod, Hunziker III, Dr. Burgess’s Atlas of Marine Aquarium Fishes, T.F.H Publications inc., 1990