Chromis viridis: All About the Blue Green Chromis

Some fish just have it all. Colorful, easy to keep, reef safe, suitable for smaller tanks… can it get any more perfect? The blue green chromis is one of these species. If you’re a beginner looking for fish to stock your first marine aquarium with, this one makes an excellent choice.

Below, find everything you need to know to make sure your chromis thrive!

This fish is also known as: damisela verde 🇪🇸, demoiselle blue-vert 🇫🇷, Blauwgroen juffertje🇳🇱, Grünen Schwalbenschwänzchen 🇩🇪, mavi yeşil reef Chromis 🇹🇷.
Please leave its name in your language in the comments!

Blue green chromis description & natural habitat

Description

The blue green chromis is a species of damselfish. Belonging to the family Pomacentridae along with their ultra-popular clownfish cousins, the damsels are aquarium classics appreciated for their small size, lovely colors, and easy care. In fact, the blue green chromis has been the most commonly traded aquarium fish of all for years!

It’s not difficult to see where the blue green chromis got its common name. Its shimmery, almost iridescent coloration does indeed fall somewhere between blue and green depending on the light.

These little reef fish reach a maximum length of around 4″, although most don’t make it past 3″.

Did you know? The blue green chromis is not always blue and green. Males, during the mating season, completely change color! They turn more of a yellow-green with some black coloration. If your fish are turning this color, that’s a good indication they’re getting frisky.

Natural habitat

The blue green chromis is a typical reef fish. It has a wide Indo-Pacific distribution and can be found all the way from the African coast (including the Red Sea) to as far east as the Pitcairn Islands.

In their natural range, these damsels prefer the shallows. They inhabit reef flats and lagoons of a depth up to around 65ft and particularly appreciate the safety afforded by “forests” of branching Acropora corals, which is where they’re most commonly spotted.

The species can form large, loosely aggregated groups known as shoals, which helps confuse predators and allows them to hunt their tiny prey (mostly plankton) more efficiently.

Blue green chromis aquarium

Although they’re quite small, blue green chromis are very active fish. This should be reflected in the size of the aquarium you keep yours in. A group of 6–8 fish, which we think is the minimum, a long tank of 75+ gallons to thrive.

Keep in mind these little damsels depend on the shelter provided by Acropora and other corals in the wild. An open environment makes them feel unsafe, so fill the tank with plenty of coral and live rock formations for them to dart around. Knowing they have a safe place to retreat to in case of danger will actually make them more bold and active!

Although they’re mainly considered inhabitants of the middle water layer, you’ll find your blue green chromis actively exploring all corners of the aquarium.

Tip: Although blue green chromis are hardy and forgiving as far as reef fish go, they will still suffer if you let the water quality drop. Ensure the tank is fully cycled before introducing any livestock and perform regular water changes to keep your chromis happy and healthy.

Blue green chromis compatibility

Most damselfish aren’t known for their ability to play nice with their neighbors. They’re notoriously territorial and can bully tankmates, including those much larger than them, relentlessly. The blue green chromis is a nice exception to this rule.

When it comes to their neighbors, blue green chromis know how to play nice. They’re peaceful and unlikely to bother their tankmates, meaning you can combine them with a wide variety of other calm reef species. If you’re a beginner, may we suggest our favorite easy saltwater aquarium fish?

As for reef safety, you’re in luck here too: this reef dweller won’t bother coral or invertebrates. The only tankmates you should actively avoid are larger or aggressive ones that might bully the chromis.

Chromis-on-chromis violence

Although blue green chromis rarely bother other species, in-group behavior is more unpredictable. Aquarists commonly report cases of “missing fish syndrome”, where the victim probably deceased but has already been eaten by its (invertebrate) tankmates.

The problem is usually a lack of space or a group that’s too small. The former means less territory to go around and more potential for fighting, while the latter can cause fish that are lower on the social ladder to be bullied so relentlessly they eventually just give up the ghost.

You can, of course, keep only a single chromis to prevent all this — but that’s a little sad for such a social species. Plus, you’d miss out on all those interesting social interactions! By giving these damsels plenty of space and keeping a group of at least 6–8 individuals, you should be able to prevent most (territorial) squabbles.

Tip: Even if you provide plenty of space and keep a sizable group of blue green chromis, they can still mysteriously disappear shortly after bringing them home. This is usually because they just don’t travel that well. We recommend buying chromis that have been at the store for at least a week or so, plus a long quarantine period to catch common infections like uronema.

Blue green chromis diet

The blue green chromis is an omnivore. It mostly feeds on small critters like plankton, copepods and amphipods, but also nibbles on algae. You shouldn’t have problems keeping yours well-fed in your tank.

Your chromis should accept pretty much anything you offer it, including commercial flake and pellet foods for marine fish. As variety is the spice of life, you can also opt to include (thawed) frozen foods like artemia, krill and mysis, plus algae tabs and blanched veggies.

Tip: Don’t over-clean the aquarium walls and rocks. Your blue green chromis will appreciate a patch of algae to graze on.

Breeding blue green chromis

Sorry, not much luck here! Fat and healthy blue green chromis will sometimes spawn without any interference on your end. The males take on their breeding colors — yellowish with a black dorsal fin — try to woo the females. This sometimes results in eggs being laid.

That’s unfortunately where things end in the aquarium. Raising the teeny tiny larvae has proven very difficult due to their fragility and free-swimming nature, which is why commercial hatcheries usually don’t bother. It’s easier and cheaper to catch blue green chromis in the wild.

Wild blue green chromis, like many other fish, are synchronized lunar spawners. This means they come together in large groups to reproduce, in this case around both the full and new moon marks. The males establish small breeding sites, which are then visited by females looking for a suitable partner and location.

Once a male chromis and his nesting site have been approved, the female will deposit her eggs. Mom doesn’t stick around, but dad does, at least for a while. The parents and larvae go their own way as soon as the eggs hatch.

Basically: yes, Chromis viridis reproduction has been cracked. Indian researchers managed it in 2009, as did the Tropical Aquaculture Laboratory in 2013. But if you want to breed saltwater fish at home, may we recommend something easier like clownfish instead?

Conclusion

A bustling reef tank with a group of shimmering blue green chromis really is quite a sight to see. We think Chromis viridis is one of the best aquarium fish for beginners, and they also make a great choice for more experienced aquarists who just want something simple.

Are you dreaming of an aquarium for your home or office? FantaSEA can help. Contact us with your ideas and let’s make it happen!