Green Chromis

Green Chromis: Chromis viridis

Green Chromis Care Guide

The Chromis viridis, commonly called Green Chromis or Blue-Green Chromis is one of the most popular fish species in the entire aquarium trade because of their very affordable price, great coloration, the boldness and energy they bring to the tank and the fact that they tend to shoal and are often purchased to creat that schooling effect in our tanks.

In the wild, the Green Chromis my grow up to 4 inches long, but captive specimens are usually only 3 1/2 inches. In captivity, the Green Chromis may live 8 – 15 years–although if you are purchasing several specimens, in order to watch them shoal (school), I predict the lifespan of all but one to be much shorter than that. But I’ll get more into that later.

Ideal habitat

In the wild, this saltwater fish would inhabit coral reef areas in the Indo – Pacific areas and are usually found in large numbers in lower water flow regions, like lagoons. They like to swim in shallow waters, with a maximum depth of 36 inches.

Although not very large in captivity, the Green Chromis do need a large tank that provides enough swimming space. According to Live Aquaria, the minimum recommended tank size is 30 gallons. I can agree with that, in principle, because these fish are active swimmers, but they are also not that large, so 30 gallons feels a bit small but also about right.

In the wild, they like to live and hide in large coral aggregations, so a tank full of SPS corals hosting a shoal of Blue-Green Chromis is a stunning display and is often what we try to create when we purchase these beautiful and relatively inexpensive (by saltwater aquarium hobby standards) fishes.
Chromis viridis 2011


These fish are planktivores, by nature, meaning they tend to eat planktonic critters like fish eggs or larva, copepods, mysis shrimp, etc.

Being planktivores, the Green Chromis is best fed several times a day (at least 3 times), as they use to feed throughout the whole day from the water column.

Behavior and tank mates

The Green Chromis is readily available in fish stores and is a peaceful fish that is thought to be generally tolerant of other Green Chromis in the tank. I have purchased 3-5 specimens at a time and placed them in my own display tanks with the hopes of creating a shoal of my own.

If you add more than one Blue Green Chromis to your tank, what you will find is that the group will form a pecking order where the dominant/aggressive fish will chase and harass the submissive, smaller fish. In my experience, this behavior happens until the submissive fish ‘vanishes’ from the tank, most times without a trace. The aggression is then directed on the next in line and so on and so forth until that one big aggressive Green Chromis is left.

I’m not sure that’s what happens all the time, but if you search on forums, you’ll find a similar story to mine in a lot of cases.

There was an article in CORAL Magazine recently, Piscine Passels: Social fishes for the marine aquarium, by Scott W. Michael. In that article, SWM recommends you keep a minimum of SIX fishes to keep the aggression dispersed adequately, although he then is quick to suggest that groups twice that size are even more likely to thrive.

Beyond their behavior amongst the shoal, the Green Chromis is generally a community-friendly, reef safe fish.

Green Chromis

Pros and cons

All in all, I’m a big fan of the Blue-Green Chromis. This relatively docile and inexpensive creature is early on the list for most people starting out in the saltwater aquarium hobby–and they make a great saltwater aquarium starter fish.


  • Inexpensive
  • Hardy
  • Can be kept in shoals
  • Active and bold behavior
  • Reef safe, they won’t attack your SPS coral, LPS coral, Zoanthids or Soft Corals


  • May carry in parasites (so use proper quarantine)
  • Will show aggression between other members of the species
  • Prone to the ‘vanishing act’


The Green Chromis is a lovely community fish that won’t cause any trouble in a reef tank. Do you have any in your tank? If so, leave a comment and a picture and show them off!


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