Galaxea Coral Care – How to Grow This Aggressive LPS

The Galaxea Coral commonly referred to as the Starburst, Crystal, Star, Tooth, or Galaxy Coral is a beautiful LPS (large polyp stony) coral popular with beginners because of its hardiness. 

Their colors are “out of this world” with awesome color combinations including tan, brown, green, pink, gray, purple, and many more! Perhaps that’s where they got their common name from, or from their long “alien-like” tentacles that can extend several inches at night. When keeping Galaxea Corals, you must note that they are aggressive. When active, your Galaxea will reach around, stinging and potentially damaging neighboring corals, which is why placement is key.


  • Common Name: Galaxea Coral
  • Scientific Name: Galaxea fascicularis
  • Family: Oculinidae
  • Origin: Indo-Pacific
  • Care Level: Moderate
  • Temperament: Aggressive
  • Lighting: Moderate-High (PAR 150+)
  • Water Flow: Medium
  • Placement: Any

Galaxea Coral Care

Galaxea Coral is a hardy coral that fits into a variety of aquarium setups. Even though they are a hardy LPS coral, extra care must be taken when handling them, as Galaxea Corals have a very fragile skeleton that can easily be damaged. 

Galaxea Corals have been widely imported and aqua-cultured for aquarists as they tend to be much hardier than corals imported from the wild. They also seem to tolerate a variety of aquarium conditions, however, you should always keep the following water conditions within range.

Ideal Water Conditions

  • Temperature: 72° – 78 °F
  • pH: 8.1 – 8.4
  • Salinity: 1.023 – 1.025
  • Alkalinity: 8 – 11 dKH 
  • Nitrates: <10 ppm
  • Phosphates: <0.10 ppm
  • Calcium: 400 – 450 ppm
  • Magnesium: 1200 – 1350
  • Strontium: 8 – 10

Feeding Your Galaxea Coral

Galaxea Corals rely heavily on the symbiotic algae that live within their tissues, called zooxanthellae. You may not be able to see them, but they play a vital role in your coral’s health and nutrition.

The zooxanthellae that live inside your Galaxea Coral provide your coral with food and in return, the Galaxea Coral gives them a cozy home to stay protected from predators. 

Although the zooxanthellae provide your coral with the nutrition they require to survive, your Galaxea will benefit from some meaty foods 2 to 3 times a week. You can give them a variety of planktonic coral foods, brine shrimp, mysis, anything meaty that will fit in their mouths. Galaxea Corals will also benefit from some supplements, just like how vitamins benefit your health. Additional calcium, strontium, and trace elements will help build their exoskeleton, enhancing their growth!

Galaxea Coral Placement

With such beautiful coral like the Galaxea, I am sure you will want to show it off, but there are a few things to consider before you add it to your aquarium.

Because of their aggressive nature, your Galaxea will appreciate being placed on an island rock away from neighboring corals. This gives them a unique position in your aquarium and ensures neighboring corals are safe from their long sweeper tentacles. As their tentacles can extend at least 4 inches during the evening, ensure you leave at least 6 inches (12 inches recommended) between other corals otherwise they will start chemical warfare, and your Galaxea will most likely win…

Placement for your Galaxea coral also depends on the lighting you provide. When kept under moderate lighting, you should place your Galaxea in the middle to the top part of the aquarium reef. If you opt for higher lighting, then you should place your coral between the middle and lower region of the reef, and if your aquarium has very intense lighting, they will best be placed on the substrate. 

Galaxea Coral Aggression

As mentioned, your Galaxea Coral is notorious for its long sweeper tentacles that can sting neighboring corals. To minimize aggression, give your coral plenty of space for them to extend their tentacles without nearby corals falling victim to their powerful sting. 

Remembering to feed them meaty treats is also a good way to prevent them from stinging other corals. If they have a full tummy they will spend less time searching for food with their stinging tentacles. 

Galaxea Coral Sweepers & Water Flow

Water flow plays an important role in your Galaxea coral’s sweeper tentacles. The stronger the water flow, the longer their sweeper tentacles usually extend, but do not blast the water flow directly at them, as they may close up. If you keep the water flow low to moderate your Galaxea may only extend their tentacles around 1-2 inches. 

So, for your Galaxea to thrive, varied medium water flow with random bursts is best. Providing this water flow pattern will remove waste products generated by organisms in your aquarium and bring enough feeding opportunities for optimum growth and coloration for your Galaxea Coral.

Galaxea Coral Lighting & PAR

Compared to SPS (small polyp stony) corals, Galaxea Corals do not require as much light and can live in a variety of lighting conditions. Unlike most corals, your Galaxea Coral can be kept under regular fluorescent lighting and still stand out from the crowd!

You must however alter their placement depending on the lighting you have. If you have chosen Metal Halides, it is recommended to place your Galaxea Coral in the low to the middle region on the reef, and with other lighting fixtures such as T5’s and LEDs, place the Galaxea between the middle and higher region. 

Galaxea Coral Growth Rate – How Fast Will Your Galaxea Coral Grow

Expect your Galaxea coral to grow pretty fast! These corals do not hang around when it comes to spreading out, however, if you are having problems with their growth, feeding often speeds up the process. 

Some hobbyists have issues with their Galaxea taking over inside the aquarium. If this happens you can try to chip off parts of the colony, however, as they are full of nasty biological warfare proteins, be prepared for many water changes. An alternative would be to remove the colony and cut parts off outside the aquarium. Do not worry, they will be fine exposed while you do that. With the cut-off frags, you can give them to a friend or sell them. 

Galaxea Coral Not Opening

Firstly, many corals do not open 24 hours a day, so monitor them for a couple of days or set up a camera, as you may be sleeping when they decide to open up. 

Secondly, check your water parameters and perform a water change if needed. 

If they continue to close their polyps, you may want to move them further up in the aquarium, so they can receive more light. Also check you are not blasting them with too much direct water flow, as your coral may not open fully to protect their polyps. Remember that Galaxea corals are very easy to become damaged as their tentacles and skeleton are very sensitive.

Galaxea Coral Dying

Galaxea Corals do not die for no reason. This coral is prone to brown jelly infections, STN/RTN (slow tissue necrosis/fast tissue necrosis), and tissue recession when they become weak. To prevent this, check your coral’s health and place it in a coral dip before adding it into the aquarium for the first time. 

Although rare, in severe cases the following issues can result in your Galaxea Coral dying:

  • Excessive debris and waste collecting between their polyps. 
  • Breaking of their skeleton, exposing their tissues to infections, and compromising their immune system. 
  • Incompatible fish (usually parrotfish and angelfish are the culprits!) that will munch on your coral’s tissue. 
  • Transport – stress, and damage can kill your Galaxea Coral, therefore keep your coral’s polyps clean and use a coral dip before you place it inside the aquarium. 

On a more positive note, your Galaxea’s polyps have wide spacing between one another, so if one polyp becomes infected or dies, then there is some hope of saving the whole colony.


Whether you are a new hobbyist looking for a coral that’s easy to care for, or you are a reef expert after a coral that has an “out of this world” appearance, the Galaxea Coral ticks both those boxes! 

  • Roy Lee

    I have an unhealthy obsession with reef keeping and maintaining successful tanks. If you haven't noticed from the website, I love everything related to saltwater tanks like coral, fish, and everything else in between. Lee Roy

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