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Blue Reef Chromis Overview, Care, Tank Setup & More

Blue Reef Chromis is a saltwater fish that is desirable among aquarists due to its attractive appearance and peaceful demeanor. The fish is coral-reef friendly that can keep with most corals, invertebrates, and community fish.

In this guide, you will learn about blue reef Chromis size, habitat, aquarium setup, water conditions, and other functional care facts.

Species Overview

Level of CareEasy
Life ExpectancyAbout 8 – 15 years
SizeUp to 4 inches
Aquarium (Tank) Size30 gallon
Water Conditions72 °F – 80 °F (22 °C – 27 °C); pH 8.1 – 8.4
Aquarium (Tank) EnvironmentSaltwater; coral
Aquarium (Tank) MatesReef compatible; any peaceful fish

Blue Reef Chromis (Chromis Cyanea) is a saltwater fish that belongs to the family Pomacentridae. Other fish in this family include clownfish and damselfish. The fish has a peaceful temperament that makes them easy to care both for beginners and expert aquarists.

It is an outstanding saltwater fish that you can keep in both reef and fish-only aquariums. The fish is highly active and darts from one corner of the aquarium to another. You can watch them swim elegantly from the middle to the bottom of the tank.

Natural Habitat

Blue Reef Chromis fish are native to the reefs in the Indo-Pacific and South Pacific regions. In the natural habitat, the fish thrives among branching corals and prefers swimming in large shoals. They are mostly found in large shoals of 100 or more.

They are commonly found in mid-depth to shallow lagoons in the wild. The fish is very active in swimming in the ocean at incredible speeds.

To feed, the fish face the current that allows them to provide planktonic foods like shrimp larvae, copepods, and amphipods.

The fish switch their diet during the summer when they are near the shores of Okinawa, Japan, eating algae, zooplankton, and phytoplankton.


Blue Reef Chromis are known for their attractive appearance. The blue dorsal side of the fish fades elegantly fades into the pale green belly. Due to the blue and green color, the fish is also called blue-green reef Chromis fish.

A group of these swimming through the aquarium will provide flashes of blue and green as the light reflects their body.

The blue Chromis species have an oval-shaped body with a distinctive forked tail. The fork-shaped tail fin allows the fish to swim at great speed.

They also have orbital papillae and small rounded protuberances on the bottom edge of the eye that reduce turbulence when swimming fast away from the predators.

Blue Chromis fish don’t have color variations. Both the male and the female have the same color. The color also remains the same as they grow. The exception is the adult male during the mating season that turns yellow with a black tail.

Sometimes this fish is confused with the black axel Chromis. But they are two different species. Blue Chromis has a shorter body, while the black axil body is slender and more prolonged. There is also no black botch on the pectoral fin of blue reef Chromis present in black axil fish.

Another similar-looking fish is the yellow edge Chromis which is native to the Caribbean. Some stores wrongly advertise them as ‘Caribbean blue reef chromis for sale.’ You can differentiate blue reef Chromis from the length of the body that is smaller. Blue Chromis fish is about half the size of the Caribbean yellow-edged Chromis.

Behavior & Temperament

Blue Reef Chromis is one of the most peaceful saltwater fish. The fish have a calm temperament.

They are not territorial and don’t attack other fish even if kept in a small aquarium. An exception is the time of spawning when they can become aggressive to each other.

Blue Chromis fish are highly active. They swim at a quick pace from one side of the aquarium to another. Watching them swim in a group of five or more can be mesmerizing. They tend to swim through the corals in perfect synchronization.

Mostly the fish swim in the middle section of the aquarium. They are playful fish that will keep each other entertained inside the tank.

The fish prefer to swim and also sleep within the coral. You should make sure that there are lots of corals inside the aquarium.

An exciting aspect of blue reef Chromis behavior is that they tend to form a hierarchy similar to the pecking order of chickens.

The weak ones at the bottom of the ranking will be the most submissive, while the ‘alpha’ fish at the top of the order will be the most dominant.

To prevent alphas from bullying weak ones, you should keep a group of at least six in the aquarium.

It will prevent the alpha from forcing other fish too much. Will spread out the aggression among the fish resulting in less bullying.

Aquarium (Tank) Mates

Blue Reef Chromis makes a great community fish. The peaceful temperament of the fish means that they can be kept with a wide variety of different fish.

It would help if you kept them with other non-violent fish such as Butterflies, Basslets, and Blennies. They are compatible with reef aquariums, and you can keep them with corals.

You can also keep the fish with semi-aggressive fish like gouramis, tangs, and angelfish. But if you see the fish spends most of the time in the corner of the aquarium, you should keep the fish in a separate aquarium from the aggressive fish. You should stay blue reef Chromis with semi-aggressive fish only if the tank is large.

And remember the more significant fish rule. If a fish is large enough to swallow blue reef Chromis whole, you should not keep it in the aquarium. The opposite is also true. It would help if you did not stay blue Chromis with a small fish that it can swallow accidentally.

These won’t harm invertebrates. I mean that you can keep them with shrimps, snails, and other small crustaceans. They are one of the best-behaved fish you can keep in your aquarium.

Ideal Aquarium Conditions

Blue Reef Chromis are hardy fish that can thrive in less than perfect water conditions. However, it would help if you still took care of water as dirty water can result in illnesses. The cleaning cycle depends on the size of the aquarium.

If you keep the fish in a small aquarium, you need to change about 15 percent of the water twice a month. For larger tanks above 60-gallon capacity, you should change about 30 percent water once a month.

Consider keeping the water temperature inside the aquarium between 72 °F – 80 °F (22 °C – 27 °C).

Water movement is not essential for saltwater fish. But if you have installed an air pump, you should ensure that the current isn’t too strong to prevent the fish from moving inside the aquarium.

Blue chromis side pose

Aquarium Setup

It would help if you mimicked the natural environment to ensure that blue reef Chromis remains happy and healthy.

Blue Reef Chromis school in large shoals in the wild. You should keep at least six in the aquarium. Adding a group to the aquarium will add a dazzling shimmer of beauty to any reef aquarium.

These are safe for reef aquariums. They will dart in and out of the coral in a group. The fish live among corals like Acropora in the wild. They do not pick on the corals either in the wild or in the aquarium.

It would help if you had plenty of corals inside the aquarium. Corals give comfort to the fish and give them a nice place to sleep.

The aquarium should also have planted sections with algae that the fish can graze on. Moreover, there should be rocks and caves inside the aquarium that will serve as a hiding place for the fish.

Blue Chromis has a petite body that grows to about 4 inches. Since their size is small, you can keep them in a small aquarium with 30 gallons of water.

Food & Diet

Blue Reef Chromis fish is an omnivore. The fish will eat both plant and marine meat. They are scavengers in the native habitat and eat whatever is available and also fit their mouth.

The fish has been observed eating larva, copepods, Mysis shrimp, phytoplankton, algae, and zooplankton. They will also eat unhatched eggs of other fish.

It would help if you fed various foods to the fish, similar to their diet in the wild. They are typically not picky about what food you give them. It would help feed the fish flakes, frozen food such as Mysis shrimp or krill, marine meat, pellets, and vegetables.

Depending on the size of the aquarium, you can feed them two to four times a day. You should give them enough food that they can consume in about five minutes. Providing too much is a common beginner mistake that can result in poor water quality and make them prone to diseases.

Breeding Guidelines

Breeding blue reef Chromis requires ideal water parameters. Both males and females have a similar color, shape, and size. But males tend to change to a more yellowing coloring during breeding. Aquarists have found that the fish tend to breed after every two weeks.

While a group of reef Chromis fish is generally peaceful, they tend to become aggressive with other species when breeding. In the wild, they don’t form pairs, and instead, several females and males mate with each other.

Each male will establish a territory near the seafloor. The males will circle the females, and they will follow to the spawning site if in breeding mode.

A male will repeat the behavior with several females until the nesting site becomes full. After mating, the female will scatter the egg on the nesting site attached to the algal mat.

The eggs of the fish are smaller compared to the clownfish. They are generally just 0.6 mm in length and 0.4 mm in width. Keeping them from being eaten by other fish will be difficult. Crabs, wrasses, brittle stars, and serpent stars will mainly eat the eggs.

Males will closely guard the eggs on their territory and keep them ventilated by fanning them. They will also eat eggs that have gone bad to avoid contaminating the rest of the eggs.

Blue Chromis eggs will hatch after about 2 to 3 days. The fish will remain in the larval stage from three to seven weeks, depending on the water temperature.

They usually hatch about an hour after dark, and they have a better chance of surviving the predators. You should feed them baby brine shrimp several times a day.

Consider placing the eggs in a separate aquarium before they hatch. It will ensure that other fish, including their parents, do not eat the young fry.

Blue reef chromis swimming towards camera

Common Diseases in Blue Reef Chromis Fish

Blue reef fish will remain healthy if you keep the water clean. Cloudy water conditions can result in various diseases. They are susceptible to viral and bacterial infections in case of insufficient quality water.

While the fish are hardy that can tolerate different water temperatures and pH levels, the fish can quickly become ill if the water quality is poor.

Blue Chromis fish will also become ill if they are stressed out. They will become tense if the group is too small or the water tank is small.

Blue Reef Chromis is susceptible to parasitic diseases. Common parasitic infections that can afflict them include marine ich (Cryptocaryon irritans), marine velvet (Oodinium ocellatum), and Uronema (Uronema marinum).

Marine ich is easily treatable if caught early. Look for white spots on the body that shows that the fish has saltwater ich.

Marine velvet is a more severe disease that afflicts blue reef Chromis. The parasitic illness mainly infects the gills and is challenging to treat.

Uronema is generally a secondary infection that is often fatal. The disease progresses quickly, and the fish dies within a few days. Fish that are afflicted with uronema display a lack of appetite. The condition is commonly contracted when the salinity level of the water becomes low.

Mainly it occurs when aquarists lower the salinity of the water to treat another condition but do not lower it enough. The parasite grows in brackish water that has a specific gravity between 1.013 and 1.020.

It would help if you treated blue reef Chromis similar to any other saltwater fish. The fish responds well to the standard treatment for these diseases.

Introducing fish caught from the wild or live rock can also introduce illnesses. You should adequately quarantine and clean anything new that you add to the aquarium.

The best prevention is to ensure that the water condition inside the aquarium is ideal. Test the water quality every week to check for any irregularity. The water should be tested to ensure good quality with no or low nitrite, nitrates, or ammonia.

Proper aquarium size, tank mates, and water quality ensure that the fish remains free of diseases. Bullying can create stress that can cause them to become ill.

So, it would help if you kept any aggressive fish separate from blue reef Chromis. Quarantine any fresh fish you buy from the pet store before introducing them into the tank. It is essential as a diseased fish will pass on the infection to others.

Where to Buy?

You can find blue reef Chromis for sale in many online and local saltwater fish stores. The fish is highly affordable, costing just about $10 each. You can buy six of them for only $60.

Make sure that you check the fish carefully for signs of diseases before buying them. Consider quarantining the fish for a few weeks before introducing them to the aquarium.

Wrapping Up

Blue Reef Chromis is a hardy fish that can live for decades. They can be successfully bred in the home aquarium. The fish are recommended for beginner aquarists.

Caring for the blue reef Chromis fish is not that difficult. You should feed a variety of food and keep the water clean.

The effort in caring for the fish will reward you in the form of a breathtaking display of shimmering shoals of blue and green. They are entertaining fish and are fun to watch and dart inside the aquarium.