Sand-sifting Starfish: A Job (too) Well Done!

Sand-sifting starfish (Astropecten polycanthus)

Sand-sifting starfish (Astropecten polycanthus)

If you’ve ever shopped for a marine aquarium cleanup crew, you’ve probably noticed that these packages often include so-called sand-sifting starfish—rather bland-colored, burrowing stars of the genus Astropecten that can reach about a foot in diameter.

As their common name implies, these stars are sold to hobbyists for the purpose of consuming detritus and uneaten food and turning over the sand bed. However, what’s often left out of the language used to market these stars as utility organisms is the fact that they tend to do their job too well.

Eating themselves out of house and home

What do I mean by this? As sand-sifting starfish move through a sand bed, they consume any edible item they come across—and that’s not limited to uneaten fish food that you don’t want to decompose and foul your tank. In the process, they also gobble up all the microfauna they encounter, such as worms, snails, tiny brittlestars and sea cucumbers, “pods,” etc.

This very efficient eating behavior has two undesirable outcomes:

  1. Very commonly, the starfish very rapidly consumes all the available microfauna and then starves to death (potentially unobserved in the sand bed, where it can decompose to the detriment of water quality).
  2. You’re left with a sand bed that’s now essentially devoid of all the life that was keeping it healthy to begin with—and that you more or less paid good money for when you purchased your live rock and/or live sand.

So, should they be avoided?

Sand-sifting startfishIn a very large system with a well-established, expansive sand bed that is several inches deep and very productive with respect to microfauna, it might be possible to sustain one. However, the odds of long-term success with these stars, even under the best of circumstances, aren’t good.

Also, don’t assume that just because a specimen survives for several months or even a year or two in your system that it’s out of the proverbial woods. A starving specimen can still cling to life for quite some time before “giving up the ghost.”

Some hobbyists report success with target feeding these stars, for example by injecting food items below the surface of the sand bed or placing the starfish directly on top of a food item, but these techniques don’t work in all cases.

The bottom line: Generally speaking, I would dissuade most hobbyists from introducing these starfish to their aquariums.

Photo credits: Hannah G, Luke Fritz

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About Jeff Kurtz

Jeff Kurtz is the Co-founder/Editor of Saltwater Smarts, former Senior Consulting Editor for Tropical Fish Hobbyist Magazine, and the aquarist formerly known as “The Salt Creep.” He has been an aquarium hobbyist for over 30 years and is an avid scuba diver.

Comments

  1. Matt Filippi says:

    Is this true with any starfish?

    • Jeff Kurtz says:

      Hi Matt! No, not all starfish behave in the same manner as the sand-sifting starfish, and their dietary needs can vary considerably.. Depending on the species, they might eat sponges, corals, other invertebrate life, algae, detritus, carrion, or various other items/combinations of items. For some species, the natural diet isn’t even known. That’s why it’s so critical to research any starfish (or any marine organisms you’ve got your eye on, for that matter) before adding it to your aquarium.

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