Why Is My Sand Sifting Starfish Losing Its Legs?

Once you have finished curating your home aquarium the hard work does not stop there. If you have chosen your fish, corals, and decorations then you will want to make sure that you keep your tank in good condition. This can involve many different things such as keeping your home tank clean, monitoring the ORP and pH levels, and keeping your fish and other creatures well fed.

Problems with fish can be easy to spot, whereas if you have any starfish these can be harder to diagnose. One of the major problems that can occur with starfish is the loss of limbs. So, here we will detail everything that you need to know about looking after a sand sifting starfish and how to diagnose problems such as losing legs.

What is a sand sifting starfish?

Sand sifting starfish are a great addition to your home aquarium as they help to keep your tank clean. They are omnivores that will happily eat any random bits of feed leftover in your tank. This can help to stop algae and other unwanted things from growing in your tank.

Many hobbyists swear by adding one of these wonderful creatures to your reef tank as there are no disadvantages, they only bring positives.

They typically live for 3-5 years and require little to no effort to look after.

Why is my sand sifting starfish losing its legs?

One of the main problems with sand sifting starfish is the loss of legs. This is an indication of health problems with your starfish. There is no set reason why sand sifting starfish lose their legs, but rather a sign that there is just something wrong generally with their health.

The environment is too warm

One of the reasons why they can lose their legs is because the climate is too warm. Because starfish are cold-blooded creatures they cannot survive in an environment that is simply too warm for them. Their legs will adjust to the temperature of their environment whereas their core (the central disc where all of their vital organs are) will not. 

Their core temperature cannot rise above 35 degrees. Once their temperature reaches a certain point the process of losing limbs beings. This is called “abscission”. 

If your starfish is in an environment that is too hot for too long then this intentional process of shedding legs begins.

Studies have shown that starfish are able to keep their core temperature 3-5 degrees cooler than their legs, suggesting that they use their legs as a protective shield against the heat. 

However, starfish are able to regrow limbs. So, if your sand sifting starfish has lost one or more of its legs then this is nothing to worry about. Simply adjust the heat conditions in your tank and then your starfish will be able to regrow their legs and live healthily without losing them again.

There is not enough food

Another reason why your sand sifting starfish is losing its legs may be that they are not getting enough food and are, in fact, starving to death. You should always make sure that there is enough food for your starfish (such as small invertebrates, shrimp and urchins) otherwise they will begin to bury themselves into the substrate in your tank and starve to death.

Once they begin to decay this can actually pollute your tank. So, you should remove your sand sifting starfish if they are unfortunately beyond the point of no return. Otherwise, you can make sure that you are feeding your starfish enough food and that the temperature settings in your tank are correct.

Is my starfish dying?

If your starfish is losing its legs then you should not be too concerned. Simply check that they are not too hot and that they are well-fed and then they will start to regrow their legs.

However, one method that you can use to check whether or not your starfish is dead is to hold them. When placed against your hand starfish should feel rigid. If they are soft or mushy then it is highly likely that your starfish is already dead.

If they are dead then you should remove them from your tank as soon as possible to avoid the decaying material polluting your home tank.

What do you feed a sand sifting starfish?

Sand-sifting starfish are omnivorous creatures which means that they will eat almost anything. It is best to make sure that they are on a varied diet so as to avoid them digging into the substrate of your tank, starving and dying. 

Examples of good food sources for sand sifting starfish are:

  • Shrimp
  • Mollusks 
  • Small sea stars
  • Urchins
  • Small invertebrates

They will, however, not eat algae. Instead, they will eat the leftover food that falls to the bottom of your tank as well as detritus and microfauna. 

So, although they are fantastic creatures to add to your tank in order to help keep it clean, if you are looking to solve an algae problem then this is not the right creature for you. Other creatures such as turbo snails and hermit crabs would make better alternatives.


Sand sifting starfish can make a great addition to your home aquarium as they keep it clean from any uneaten food and they also provide a more interesting sight than simply adding more fish. However, you should always make sure that they are kept in the right conditions.

One of the main signs that they are having health problems is the loss of legs. If your starfish starts to lose its legs then there are two main things to check for: the temperature of your tank and how much food they are getting.

If your tank is too warm then the sand sifting starfish will sacrifice its arms in order to keep its body temperature at the right level. You should then adjust the tank’s conditions to avoid this happening again. Otherwise, ensure that they are getting enough food and not starving to death.


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