The marine hobby is full of territorial and aggressive species. Few are as notorious as damselfish. Can you keep any of them in a community aquarium? Marijke investigates.
“Damselfish” is a common name used for a group of small, colourful marine fish that inhabit coral reefs around the world. This is not a scientific term. Instead, it is a way of grouping together similar-looking fish within the Pomacentridae family.
All damselfish are Pomacentridae, but not all Pomacentridae are damselfish. This group of fishes contains one non-damsel genus, namely Amphiprion, which you might know as clownfish (pictured below)!
All images by Shutterstock unless otherwise stated
Clownfish have unmatched popularity outside the aquarium hobby, but damselfish steal beginner aquarists’ hearts with their beautiful colours. You can find damsel genera like Dascyllus, Chromis, and Chrysiptera for sale in almost any aquarium store. Their small size and hardy nature make them endlessly attractive to new reef hobbyists.
The species you’ll come across most frequently is a gorgeous neon-hued number known as the green chromis (Chromis viridis). They consistently rank as the top most commonly traded saltwater fish in the hobby.
Photo by Alex Bell
On paper, damselfish are the perfect aquarium fish: small, colourful, forgiving of beginner mistakes, feed well in captivity and cheap to buy. However, reefing is never that easy.
Related article: Marine starter fish to avoid
Damselfish aggression
Most damselfish are proof that size is not everything. If you thought their clownfish cousins were feisty, you’ve got another thing coming.
Scuba divers will know these small fish are not intimidated by your size; they will go out of their way to get in your face. They move at lightning speed and regularly attack my camera and hands.
The same happens in the aquarium. Tank mates commonly end up on the receiving end of damsel wrath. If you desire a peaceful community aquarium but also want a damselfish, you’ll have to choose carefully.
Normal measures, like adding territorial species last, are usually not enough with damselfish. Serious territorial aggression will soon erupt in your reef aquarium. Now it is time to look at some of the best and worst options to consider.
Stegastes planiforns show plenty of interest in my camera when diving - Photo by Marijke Puts
Related article: Marine fish with character.
The 'nice' guys
Because damselfish are so prone to violence, it’s important for beginning aquarists in particular to choose wisely. The last thing you want is for your beautiful new reef tank to turn into an underwater soap opera. Some reefers will avoid all damsels like the plague on principle, but there are actually some that get along alright with most tank mates. Most of them belong to the genus Chrysiptera, although Chromis also contains some good beginner marine fish.
Green chromis (Chromis viridis)
As I’ve already mentioned, the green chromis is the most common saltwater fish in the aquarium hobby. That tells us something about its disposition. This fish would not have reached the top spot if it was not at least suitable for some community tanks.
Indeed, if you’ve kept C. viridis, you’ll have noticed it’s unusually mellow for a member of the Pomacentridae. These cyan stunners are hardy, social, reef-safe, and easy eaters. They will often leave their tank mates alone, too.
However, in cramped conditions, small groups in particular have an annoying penchant for “thinning the herd”. One by one, the shoal reduces in size as they murder the weakest of the group. Keeping a sizeable group of at least 6-8 fish with enough territory for everyone can go some way in preventing Game of Thrones-esque situations.
Limiting yourself to a single fish also works for small tanks of around 115 litres (25 gal). However, you’ll miss out on a lot of the interesting social dynamics. In the wild these fish are occur in large shoals so it is best to go for a group of 6 or more in a 280-litre (62 gal) aquarium.
Blue chromis (Chromis cyanea)
Naming within the genus Chromis isn’t very creative, both their scientific and common names are often based on their colours. So, unsurprisingly, the blue chromis is indeed bright electric blue, but with some black accents on the fins and upper back.
All the previous facts on green chromis apply to this closely related species, too. Some aquarists report the blues being slightly more assertive than the greens. This is likely because they’re also a little larger. Still, these damsels are unlikely to bother their tank mates if you house them in the same way as you would green chromis.
Azure damselfish (Chrysiptera hemicyanea)
This damsel is definitely one of the prettiest. The azure damsel is a small fish, reaching a maximum length of 7.5cm (3”) but it's impossible to overlook. They display an electric blue head/back and neon yellow belly/tail.
The Chrysiptera damselfish are not quite as passive as the Chromis. Still, most aquarists find them manageable in a carefully planned marine aquarium. We have a few different ways to approach keeping Chrysiptera.
Most aquarists like to buy two fish that have already paired off in their local fish shop. This often reduces intra-damsel aggression but it can result in more frequent territorial squabbles during mating time. Saltwater aquariums of 210 litres (46 gal) or more will be suitable for pairs.
Keeping just one damselfish works too. They won’t be quite as bold and jerkish on their own but they do then lack some of their character. Home aquariums as small as 115 litres (25 gal) will work for just one adult damsel.
If you get a group, go for at least 6-8 fish in a large tank, but keep in mind that not all of them will always make it. The more space the better, and ensure there's plenty of cover for subdominant individuals to seek shelter. Branching corals work well, as this is where azure damselfish often live on the corals reefs.
Other popular Chrysiptera
A few other popular choices from this genus also deserve a mention.
Talbot’s damselfish (Chrysiptera talboti) sport a canary-yellow face and is easy to recognise by the dark eyespot on its back. The rest of the body can range from a rosy grey to an intense blue or purple depending on factors like age and mood (which is normal in damselfish).
The yellowtail damselfish (Chrysiptera parasema) is another colourful option. However, multiple damsels respond to the common name “yellowtail” so be sure to get the right one. Ensure you avoid the larger and seriously bad-tempered Microspathodon chrysurus.
The blue sapphire damselfish (Chrysiptera springeri) has a dark metallic hue making it a little more understated than the others on this list. But it is still a certified eye-catcher, and just as friendly, that’s if you can say any damsel is friendly.
Damsels to avoid
As we’ve seen, some damselfish can play nice. This is unfortunately more of an exception than a rule. The rest of the 30 genera ranges from spicy to fully unhinged.
Most of the larger and more territorial damselfish wisely stay in the ocean. However, some of the smaller and particularly colourful species do pop up in aquarium stores. They don’t usually come with a warning sign on their tanks, so you will need to keep an eye out for them yourself.
Fishes from the genus Dascyllus are quite common. While lovely to look at when small, they don’t have quite such lovely personalities. The domino damselfish (D. trimaculatus), pictured above, and the humbug damsel (D. aruanus), pictured at the top of the page, are the most common species. I would recommend avoiding these fish no matter what.
The first damselfish I ever met in the wild were from the Stegastes genus and they promptly attacked me. They may be very pretty to look at and easy to keep in the aquarium, but contains species that are mean even by damselfish standards, such as the three-spot damsel (S. planifrons). One publication I came across suggested giving these fish as Christmas gifts to aquarists you don’t like. Quite a devilish move, particularly because damselfish are almost impossible to catch out of a mature reef tank.
Another genus to watch out for is Pomacentrus. The beautifully blue P. pavo is somewhat common in the aquarium trade, while P. caeruleus can sometimes be confused with one of the more placid species – the azure damsel. Not the worst as far as damselfish go, but although these start out cute, they develop a mean streak as they age.
Finally, divers and snorkellers will be familiar with Abudefduf, also sometimes known as the sergeant majors, pictured above. These mostly striped fish can be found hanging out below pretty much every boat and jetty in the Pacific. They’re always on the go and happy to snack on anything from plankton to bits of sticky rice dessert.
As lovely as they are when you encounter them in the wild, sergeant-majors can cause chaos in the aquarium. They’re gregarious, fast, and territorial, not to mention big: some species can reach 18cm (7”), significantly larger than the average damsel.
Caring for damselfish
While our ‘nice guys’ can thrive in certain community set-ups, single species tanks are best for some of th others. This is not just for their tankmates’ sake, but also their own. The presence of other fish just seems to drive some of them completely nuts, which must be quite stressful.
For the community-suited Chrysiptera and Chromis, your best bet will be tank mates that are peaceful but not pushovers. No sensitive mandarins, but also no large, boisterous wrasses.
Clownfish will work if there’s enough space and rockwork to go around, and so will inoffensive cleaner shrimp, hermit crabs, and snails. As for corals, you’re in the clear here. Damsels don’t appear interested in grazing on or picking at them at all, so they’re safe with LPS, SPS, and softies.
Related article: Back to saltwater: starting simple with beginner corals.
Unlike some marine fish, they’re not picky about their meals at all. They will generally adapt to eating prepared aquarium foods (as well as the typical frozen foods) without issue.
Chromis and Chrysiptera, like most of their kind, are micropredators. The majority of the Chromis diet consist of pelagic planktonic copepods. Although, some species also feed on floating fish eggs.
Chrysiptera, on the other hand, generally likes benthic prey. They often search the seafloor, or amongst the live rock in an aquarium, for their meals. For an aquarist, all we need to know is that our damsels will appreciate two meals of meaty fare a day.
So, are damsels all bad?
Small but mighty, damselfish have perfected the “attack first, ask questions later” lifestyle. This has given them great success in the harsh, fish-eats-fish environment of the coral reef. However, it also makes them problematic in the aquarium.
Luckily, there are exceptions. If you want all the damsel but none of the Napoleon complex, some of the Chromis and Chrysiptera do make excellent choices. The real damselfish enthusiast can even consider setting up a single-species aquarium. The colours and active nature of the members of Pomacentridae make them more than worthy of the spotlight!
This article was first published in the July 2025 issue of Practical fishkeeping. Subscribe today for more fishkeeping advice, top tips and amazing tank builds.