Green Star Polyps Not Opening- How to Treat & Keep Vibrant 

I feel so disappointed when I find that my green star polyps are not opening. As they create a lively look in the aquarium, I always try to keep them in my tanks.

However, due to salinity, incorrect placement, algae growth, pests, improper light and water flow, acclimation problems, and unwise selection of tank mates, green star polyps are not open.

If you are also going through the same situation, then you are at the right place. I am going to describe the ways to keep your green star polyps safe and sound.

8 Reasons That Hinder Green Star Polyps From Opening 

1. Incorrect Placement 

Let’s start the description part with incorrect placement. I am talking about their placement inside the aquarium. 

Many hobbyists, especially beginners, commonly make the mistake of placing them in an incorrect place. It happens in most cases if you don’t study more about them as I did the first time.

Whenever you are placing them, you should be concerned that they should not remain in the upper part.

If they remain in the upper part, they get too much light condition. Such lighting creates an unsuitable condition for them. As a result, they don’t feel comfortable to be open and remain closed. 

2. Salinity

Next, let’s talk about salinity. Salinity Issues also may prevent green star polyps from opening. As these corals are mainly freshwater lovers, they can’t live freely in salt water.

There is a specific salt level for green star polyps that I am going to mention in the remedies part. Whenever you place them in a more salty condition, their body part feels barriers in different mechanisms.

As a result, they feel the ecology is an adverse condition and don’t open at all. Until you sort out the salinity problem, it may not open. 

3. Improper Light 

Not only the salinity of the water but also the light condition you are providing to them is also important for the green star polyps to thrive. 

Similar to the salinity level, there is also an optimum light intensity for these corals. Whenever you are placing them much closer to this light condition, most probably it may get extreme for them.

On the other hand, if you place too low, enough light may not reach them. Unfortunately, both of these reasons can be problematic for them and responsible for their closed condition. 

If your green star polyps are not opening, you can check the light intensity of your aquarium with the ideal measurement that I am going to mention below.

4. Water Flow

Already, I have discussed the salinity problem of water. Along with that, I should also mention water flow which is a mandatory issue for their undisturbed livelihood. 

Green star polyps get a soothing movement if the water flow is medium. Slow water flow rate makes their movement slower or they tend to stop their movement. 

Again, high water flow is problematic for their natural opening. As they can’t cope with the high water flow, they usually remain closed.

5. Pests

Pest attack is a different but common issue for green star polyps not opening. Pests are mainly the pathogens that attack green star polyps inside the aquarium. 

Sometimes, different small insects or micro-organisms parasitize these corals. As a result, they take the nutrients from the corals and make the polyps unhealthy. 

Also, these pathogens create diseases and the coral population gets attacked with them very fast due to their spreading nature. 

Within a short time, the whole population gets attacked and they can’t open because of their unhealthy conditions. 

6. Tank Mates

Meanwhile, you have learned about the stressful conditions inside the aquarium due to the water condition. But do you know that tank mates can also disturb them?

If you keep any voracious fish or aquatic inhabitants in your tank, they can be harmful to the polyps. Consequently, they can’t live freely or without stress and don’t open naturally.

Predatory fish may eat them too. Hence, you should be careful about the selection of your tank mates to save their safe circulation. 

7. Acclimating Problem

The acclimating problem indicates the adjusting problem of the polyps to their surroundings. In the case of a new arrival, suddenly they may face problems adjusting to the aquarium. 

Most importantly, if the aquarium or tank set-up is not optimum for them, they may die also due to the adverse condition. 

Also, as they are detached from a colony, they need some time to adapt to their new surroundings and manage their body mechanism to interact with them.

Every component like water quality, light intensity, and abundance of food should be available for them so that they don’t get any stress and can adapt to the new environment. 

8. Algal Growth

Lastly, I am going to end the list of reasons by pointing to the algal growth. Sometimes, algae grow on them and due to this reason, they don’t open.

This algal growth is one kind of parasitism that receives food and nutrients from the polyps and also covers the opening point of the polyps. Thus, they can’t open.

How to Open Green Star Polyps 

In the upper portion, I have mentioned that there are some criteria that help your polyps to remain in a healthy surrounding and also helpful for them to open. Let’s start with their caring issues. 

To enjoy the blooming of green star polyps, you have to first make the ecology of the tank balanced and optimum for them.

For that purpose, make sure that you have introduced them in a freshwater tank. Or, if you are taking them to a saltwater tank, the salinity should be between 1.020-1.026. 

The following terms come about their placement. You should not move them from one place to another. Also, place them on such a side that they can get bright light intensity. 

As I mentioned, darkness or excessive direct light is injurious to them. Also, keep them properly adjusted with the reef tank. 

Next, arrange a proper diet for them to keep them healthy. They mainly absorb their nutrients from the water body.

But, you can also add some supplementary food for them. Also, keep your water quality higher so that pests cannot attack them and do any harm. 

As they take nutrients from water, the water elements should be balanced. Otherwise, it will get toxic for them.

At the same time, be conscious in selecting tank mates for them. Aggressive fish or snails should not be kept around them that may be harmful.

Along with mates, you have to also be concerned about the algae growth. If algae grow on the coral, clean it gently with a smooth brush so that the corals remain undisturbed. 

Additionally, you have to be conscious about the current water flow of your tank. It should not be too much or too low which is harmful for their moving. 

Lastly, let them take some time in the tank while adjusting. Whenever they are new to the tank, they need to change some mechanism inside their body. So let them adapt to the new environment. 

Thus, you can make the green star polyps open by manipulating their different aspects.

How Long Does it Take Green Star Polyps to Open?

Green star polyps take 2-3 days to open. But this is applicable when you are putting your green star polyps in the right condition.

I have already described the perfect condition or atmospheric requirement needed to thrive green star polyps. If you can maintain those, hopefully, they will open in 2-3 days. 

But being a hardy coral, they may need 1 or 2 days more. You need not to be tense for this. They are going through their natural process.

But if the corals take more days than this, you should check the parameters of their ecology and take the necessary steps for them.

How Do Green Star Polyps Look Like During Closed?

If you have been nurturing green star polyps for a long time, hopefully, you are familiar with their closed look as they are a little sensitive to their nature.

A closed green star polyp looks like a grey surface having blue bumps on it. The opening points remain shrank and accumulate at a point.

As a result, the strings take a bump-like appearance. But it looks like a green grassy structure when they are open. 

During the opening, the green parts flow with the water as if the wind is blowing in the grassland. Due to this beauty, hobbyists adjust green star polyps in their aquariums. 

Can Green Star Polyps Die Due to Closing?

This fact is not related to their closed nature but rather to their relation to their surroundings.

Whenever the green star polyps are closed, it means that they are not getting their optimum condition for survival and they need to be rescued from them.

Also, they are not able to complete their natural process of opening. It also affects their body mechanism. If you don’t take the necessary steps to protect them, they will die within a short time.

At that period, they will also start to decompose by the bacteria, and within a few days, the aquarium atmosphere will be destroyed and polluted for the other organisms.


Do green star polyps need calcium?

Yeah! Green star polyps need all types of nutrient materials or minerals like nitrogen, potassium, phosphorus, and calcium which they can absorb from the water and need a little from the supplementary food.

Do green star polyps close at night?

Always! You can see green star polyps moving during the daytime in the natural phase. They only close at night and the time when they are going through stressed conditions. 

Are green star polyps easy to care for? 

Of course! Green star polyps are one of those corals which you can nurture in low maintenance. You have to complete their general requirements for living.

Final Thoughts

Let’s end the description here. Green star polyps are one of the most common and favorite corals of hobbyists like me. 

Their moving nature creates a vibrant and lively look in the aquarium. That’s why you should be conscious about them so that all the requirements of them can be fulfilled. 

If you can properly maintain them, your green star polyps won’t bother you by closing suddenly and thus your aquarium will also have a gentle and lively appearance. 

Howard Parker

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