I am an Affilate!

I sincerely hope you love any product or service that I recommend. :) Just to clarify, I may take a share of any sales or other compensation from the links on this page. As an Amazon Associate I earn from qualifying purchases. If you use my links, great, I appreciate your support.

How Many Green Chromis in a 30 Gallon Tank?

So, How Many Green Chromis in a 30 Gallon Tank?

One Chromis can be easily kept in a 10 US gallon marine aquarium. 

To answer the question, 5 to 6 Chromis in a 30 Gallon tank is the maximum.

A school of six will also help in keeping the 'alpha' from bullying the more submissive of your Green Chromis.

It is important to keep them together in at least six groups so as to prevent the alpha’ from bullying the individual fish a lot. Therefore, this practise helps to spread out any possible aggression. Oh yes! Do remember to change 5 to 15% of tank water on a bi-weekly basis.

Where Are They Originally From?

This species was discovered in 1830 by Cuvier, according to ncbi. Did you know that the Green-Chromis are mostly found in tropical and subtropical waters?

Distributed over a wide area, they are found in large numbers in the Great Barrier-Reef, the Indo Pacific region, the Red Sea, Madagascar, the Gulf of Aden, Indonesia, and New Caledonia. The preferred habitat of this species is sheltered sub-tidal coral reef flats and lagoons.

They are mostly found at a depth of 5 feet to 39 feet. Huge aggregations of this fish are seen hovering around thickets of branching corals especially Acropora corals where they seek shelter and refuge for the night.

The fact that coral colonies are eaten by crown-of-thorns starfish is leading to coral depletion. This is adversely affecting the settlements of Green Chromis.

Being non migratory by nature, their need for their preferred habitat is being compromised by ecological imbalance. Nonetheless, do remember to furnish your marine aquarium with coral rocks. This would ensure green Chromis as natural a habitat as possible.

What Is Their Scientific Name?

You may hear Green Chromis being referred to by a host of names such as Blue-Green Reeffish, Green Puller, Blue-Green Reef Chromis, the Blackaxil Chromis or even Blue Green Damslefish.

The reason behind this is simple. Its habitat and distribution covers a vast area, hence in different parts of the marine world this spectacularly colored fish is known by different names.

Sometimes it is also referred by a scientific name - Pomacentrus Viridis. However you should go by its scientific name which is Chromis Viridis.

Are They Also Called Blue Green Chromis?

Green Chromis can be classified as a member of a humongous Pomacentridae family of the Damselfish and the Anemonefish. It comes from a subfamily in the Chromis genus and its scientific name is Chromis Virdis.

Commonly referred to as Blue Green-Chromis, Green Puller it is sometimes mistaken to be similar to the blue puller, which is a close relative. It takes its name from the brilliant hues of green and blue which it exudes depending on the light that comes through the aquarium tank.

There are as many as 100 recognized species of this genus. Not every species is used for fish keeping. This species is as yet not listed on IUCN's Red-List of Threatened Species. Damselfish is generally perceived to be an aggressive fish.

However, Green Chromis displays a relatively calm disposition, which is compatible with fish of its own species as well as other species of fish, corals and other invertebrates. A hardy species it is generally found in large schools counting up to hundreds but easily survive in as small a group of five to six in an aquarium.

What Do Green Chromis Eat?

Interestingly, the dietary behaviour of Green Chromis in the wild is variant from that in a marine reef aquarium. In its marine habitat, it primarily feeds on planktonic foods like fish eggs, copepods, and worms as well as larvae of the shrimp and amphipods, according to ​animal-world.

In certain regions during warm temperatures, it can be found feeding on filamentous and floating algae. Incredible as it may sound, male Green Chromis would not think twice in feeding on its own eggs, provided they have failed to hatch!

You would find your Green Chromis happier if you feed it on meatier foods such as chopped fish, brine shrimp, or shrimp is also a great hit. Proportion of vegetable diet required is much less for this fish. Remember to wet the pellets thoroughly so that you ensure to keep them from ingesting air.

Do not be surprised to see the dietary requirement of this relatively small sized fish. While in the wild, it is almost always eating, so you also preferably feed it two times a day. This fish is fond of variety and will thrive if given different kinds of fish to eat.

What Does Green Chromis Look Like?

Green Chromis usually is a delight to observe and believe me, you would not regret having it in your marine aquarium. Active and playful, they are constantly swimming.

The fish generally grows up to 10 centimetres but again could grow bigger or longer than that depending on the favourability of its habitat. Its compact, sleek body has hues of intense blue and green color which are alive to changes in light.

This makes it exceptionally beautiful. The only other color on its body is a silver streak under its eye. It has 12 dorsal rays and of these, 9 to 11 are soft dorsal rays. It has two anal spines and 9 to 11 soft rays on its fins.

Remember your pet will also secrete mucus which may seem slimy. Nothing to worry about though as it does so to keep parasites and threats at bay.

Did you know that you could spot the male during the breeding season? How? Just watch your male Green Chromis turn yellow or muted greenish yellow during the mating season. Interesting indeed! Watch these alluring fish:

What Is Their Behavior Like?

Unlike other damselfish which are aggressive, Green Chromis are vibrant, active and peaceful fish that loves to swim. In your aquarium, they would easily gel with many other community fish. 

Remember that Green Chromis loves to keep company so preferably keep a school of six.

While freshwater fish loves movement in the water body, Green Chromis doesn't like swimming in fast currents. In fact, you would be mesmerized upon to watching them swimming throughout the corals of the aquarium in synchronization.

Watching Green Chromis play with one another in an aquarium is a very thrilling experience. It is interesting to note that this fish generally swims in the middle- section areas of the water-column and when it’s sleepy, it will dunk into the coral reefs you have put up in the aquarium.

Jealousy could make them aggressive. So if you are thinking of breeding them, be careful as you can watch them grow aggressive! This fish is not venomous but one interesting trait is that they like to pick on each other.

Do your own case study - add a new Green Chromis to your existing school and then watch as they acclimatize to the change.

Can You Mix Green Chromis in the tank with Other Fish?

Yes, you indeed can. Even if you are an amateur fish keeper, there is nothing to worry. It is a very easy marine fish to keep in a marine aquarium. Perseverant and hardy, it can be easily kept with other tank mates. However, you will have to exercise restraint.

While Green Chromis is mostly docile, you do have to be alert that it is not being picked upon by its pugnacious, aggressive tank mates, like Firefish. Be alert for this could make your pet more than grumpy - it can fall sick.

Do not keep it with larger predatory fish, as it may become their prey. Groupers, tangs, lionfish, and eels all present an element of danger for this species. They are more at ease with friendly fish like Basslets as well as Butterflies and Blennies.

The most ideal would be keeping them together in a school of six. Interesting thing to note is that even when Green Chromis is swimming with its own kind it tends to set a hierarchy - the toughest swim at the top while the weakest languishes in the middle of the tank, according to fishKeepingWorld.

What Is The Best Tank For Them?

You may find difficulty in ascertaining the most appropriate tank for fish keeping especially if you are an aquatic beginner. No worries, this article will give you the lead insights essential to make the right choice.

You could choose between a saltwater aquarium or a mini reef. If you are deciding upon a saltwater aquarium, make sure that it is furnished with corals and rockwork which create natural crevices.

Green Chromis is tuned to look for shelter so branching coral would be a great add on. In reef aquarium, you could use live rock or artificial coral reefs which are similar to Acroporas the natural habitat of this fish.

Also add areas infused with algae growth as food for them to nibble upon. This fish tends to swim at the upper regions of the tank, so ensure that the upper areas have relatively more space for it to be able to swim.

Make sure that you meet the apt water conditions or otherwise disease would infest your Green Chromis. To watch Green Chromis in a reef tank access this video:

What About The Water Temperature?

You have to keep the temperature mostly steady for your Green Chromis. When it is time for Green Chromis to breed (your muted greenish yellow male Green Chromis will alert you) it is time to change the temperature.

The temperature of the water should ideally be maintained between 72.0 to 82.0F, with a pH that ranges between 8.1 and 8.4 as well as a specific-gravity of about 1.023 to 1.025. Take care that you increase the temperature and keep it stable between 79.0 to 82.0F during the fish's breeding time period.

This would ensure that your fish gets temperature settings that are optimal for laying and hatching of eggs. Ensure that the water in your aquarium is not brackish and should have a Carbonate Hardness (dKH) of 8-12.

Watch your fish come alive in multiple hues. But why do you need an ideal temperature? Well, it affects virtually all facets of the Green Chromis’ existence, from the breeding in case you are keeping them for this purpose, to keeping warm and generally ensuring it remains active inside the pond.


So do you feel you know your Green Chromis any better after having read this article? Sure you do. It sure would be a great guide for enthusiasts of fish keeping and saltwater beginners. 

Green Chromis, indeed, is a remarkable species currently not listed on IUCN's Red List of Threatened Species. Lets hope it stays that for ever, and we can enjoy them for many years to come.


Hey, thanks for passing by, welcome to the blog for Pet Fish fans. This is me, Wayne, and my son Theo. I started this journey after we bought him hist first Fish Tank of fish. Follow my site for my research and info on Pet Fish.