Mates, Diet, Behavior and Size

Welcome to our Blue Devil Demoiselle care guide! If you’re a saltwater aquarist looking to add a splash of bright blue to your aquarium, you’re in for a treat. These striking fish, known as the Blue Devil Damselfish, can bring a lively and captivating presence to any marine setting.

In this guide we will share our knowledge and ideas to help you provide the best care for your Damsel Blue Devil. From their preferred habitat and feeding habits to their unique behaviors and tank compatibility, we’ll cover everything you need to know.

Whether you are a seasoned hobbyist or new to the world of marine aquariums, we are here to help you create a thriving and harmonious environment for these captivating creatures.

Let’s dive in and explore the fascinating world of Blue Devil Damselfish together!

Species Summary

The Blue Devil damselfish is known as the blue damselfish, blue damselfish, and South Sea damselfish. Its scientific name is Chrysiptera cyanea, and it belongs to the Pomacentridae family. They can be found around the Indo-West Pacific including Western Australia, the Great Barrier Reef and the Ryukyu Islands.

They are mid-to-bottom dwellers and their natural habitat is rubble and coral. Additionally, they like to hide near protected lagoons and subtidal coral reefs. A frightened damsel even hides in a crevice for protection.

Author’s note: Despite their behavior when scared, these fish are territorial and aggressive with certain other fish.

Additionally, the Blue Devil Demoiselle is a resilient species that can defend itself against certain species and diseases. As for their tanks, they strive in salt water conditions. They can also be placed in a fish or reef aquarium to co-exist with carefully chosen tank mates.


The Blue Devil damselfish is a unique little fish. Its bright blue body stands out in its tank and its bold color scheme is why this fish is so popular among aquarists. The snout and tail of the male fish are yellow, while a black spot can be found on the dorsal fins of female and juvenile fish.

A Blue Devil damselfish swimming in a saltwater aquarium


The average lifespan of the Damselfish Blue Devil is two to six years. In captivity, fish can live up to 15 years with proper care.


The average height of the Blue Devil damsel is 2.8 inches, but it can reach 3.4 inches. It is one of the smallest fish you can add to your aquarium.

Blue Devil Damsel Care

As mentioned earlier, the Blue Devil Damselfish is a good fish for beginners because it is easy to care for. In addition, these fish adapt well to captivity, so they do not need special care to get used to their aquarium.

It’s always important to make sure your fish get the proper care, and you can start by providing them with a comfortable, livable environment. This ranges from providing an appropriate tank size to creating the right water parameters.

tank size

A minimum tank size of 20-30 gallons is recommended for a single or pair of Blue Devil Damsels. If you are housing more than two fish, it is best to provide a 55 gallon tank. This way your fish have enough space to live together comfortably.

Water parameters

Providing the right water parameters is essential for more than just creating a comfortable atmosphere. You also need the right water parameters for breeding purposes.

Water temperature: 72 to 84 degrees Fahrenheit (22.2 to 28.9 degrees Celsius)

pH levels: 8.1-8.4.

Water hardness: 8-12dKH.

Specific gravity: 1.020-1.025.

Tank configuration

You can easily keep your damsel in a well-maintained tank with bi-weekly or monthly water changes. This is important for providing a clean environment and a source of nutrients, so we’ve included the guidelines below to help you determine how much water and how often you should change it depending on the type and the size of your aquarium.

Fish tanks only

  • Nano and small tanks up to 40 gallons: 10% water changes every two weeks or 20% water changes monthly.
  • Medium tanks up to 90 gallons: 15% water changes every two weeks.
  • Large tanks of 100 gallons or more: Depending on the bioload in the tank, you can change the water 10% every two weeks or 20% every month. However, you need to wait until the water is older and stable.

reef tanks

  • Nano and small tanks up to 40 gallons: 15% water changes every two weeks.
  • Medium tanks up to 90 gallons: 20% to 30% per month, depending on bioload.
  • Large tanks of 100 gallons or more: 20% to 30% every six weeks, depending on bioload. Again, wait until the water is older and stable.

Are Blue Devil damselfish reef safe?

The Blue Devil damselfish is reef safe, so you don’t have to worry about your fish disturbing your corals and invertebrates. Plus, you can rest assured that your fish are safe in a reef tank.

Possible common diseases and prevention

The biggest problem for a Blue Devil damsel is stress during shipping. However, there have been records of these young ladies suddenly dying. When this happens, they may have caught a common disease from other saltwater fish. Luckily, the Blue Devil Damsel is a tough fish, so this is a rare occurrence.

Although it is rare for Blue Devil damselflies to get sick, they are still susceptible to parasites such as Crypt, Marine Velvet, and Uronema disease. The good news is that all of these pests can be treated if caught early.

Of all the diseases, the one that is relatively easy to cure is crypt or salt water. Sea velvet, on the other hand, must be treated quickly since only a few fish have been identified to be able to generate a natural and sometimes temporary immunity to this disease. Also, if you find your fish with a lack of appetite, it could be Uronema disease which is quite deadly.

Author’s note: One way to treat illnesses is to use live foods, such as worms, fish, and shrimp, and always be sure to properly clean and quarantine items before adding them to the tank.

Food and diet

Blue Devil damselflies are omnivores and their diet consists of both meat and vegetables. They like to feast on a variety of foods, including seaweed, fish eggs, brine shrimp, and worms. You can feed them both frozen and live foods, but live foods are not a required source of nutrition.

Also, some damselflies accept flakes and pellets, but you must use tank water to wet the pellets before feeding them. Otherwise, the air from the pellets could get into your fish’s digestive tract.

Author’s note: You want to feed your damsel several times a day, but each meal should be done in small amounts to avoid aggression.

Behavior and temperament

Blue Devil Damsels can be aggressive, so they may not be the best choice if you want a strictly peaceful tank. Female and juvenile fish are not as aggressive, but males can be aggressive and territorial as they mature. So pay attention to the male to female ratio when adding your damsel to a tank.

You can place a male and several females in the same tank, but you must provide several hiding places. You can also keep a male and female pair in the same tank, but you can always create multiple places to hide.

Keep in mind that damselflies can prey on smaller or less aggressive species, so it’s best to place them in a community tank with larger or moderately aggressive fish.

A Chrysiptera cyanea looking for food

Blue Devil Lady Tank Mates

When you think about their temperament, the Blue Devil damselfish lives up to their name with their demeanor, so don’t even try to pair them with calm fish like the Mandarin Goby or Lawnmower Blenny. However, it is possible to keep them with certain teammates which could include:

Of course, you should avoid placing your lady in a tank with its predators, such as brittlestars, crabs and wrasses. These species are known to eat damsel eggs.


If you want to breed your Damsel Blue Devil, you must pair a male and a female in the same tank. Remember that it is easy to tell male and female apart by their appearance.

You also need to create the right environment for breeding. For example, the temperature should be set to 79 degrees Fahrenheit. The best temperature range for breeding is 79 to 82 degrees Fahrenheit (26 to 28 degrees Celsius). Live foods such as shrimp, fish, and worms can also be used to encourage reproduction.

The male’s territory is close to the nest site, and the female visits all the males in her colony to select a suitable nest for her eggs. She is very picky about which nest she chooses for her eggs, so she takes her time choosing a male for spawning. Once she makes her decision, a ring of light flashes around each eye as she gazes upwards.

In captivity, your aquarium can only hold one pair, so the female already has a spawning mate. The male damselfly guards the eggs until they hatch, which can take up to four days. Remember that the larval stage can take 10 to 50 days.

Author’s note: There can be over 10,000 eggs in a nest site, and males sometimes abandon the nest to take a bigger one. Remember that eggs and larvae are small, so feeding and caring for them can be difficult.


We hope you have found our Blue Devil Damselfish care guide informative and helpful in providing the best care for these mesmerizing marine beauties. Now you have learned about their preferred habitat, food preferences, and tank compatibility.

Remember to create a suitable environment with plenty of hiding places and choose tank mates carefully to promote a harmonious community. Watching these bright blue fish swim gracefully in your aquarium can be a source of joy and awe.

As you continue your journey into the world of saltwater aquariums, we encourage you to continue to deepen your knowledge and explore new aspects of this fascinating hobby. If you’re looking for more knowledge, feel free to check out our other saltwater care guides and maybe even tag us on Facebook when you post a cool photo of your aquarium.

Happy fish farming!

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