There’s a new word in town… Aquilonastra. Look for the ‘Links tab’ to find in-depth research articles on how it came to have a new name. The term Asterina has to be one of the more frequently words used in our hobby, for it belonged to a genus of starfish frequently hitchhiked into our tanks. Because of this, it’s going to be next to impossible to correct the usage of the term in conversations and write ups. It still belongs to the family Asterinidae, but that’s really not helpful when trying to predict their behavior as it’s just too broad. There are 28 of these small guys if you wanted to do any deeper research into a particular species.
They used to get a thumbs up from everyone as far as their suitability in our aquariums, yet the tides have changed for these little guys. I believe it was Garf.org that originally ID’d an issue with them eating coral, but that attitude didn’t gain popularity until recent years. These days, when one is ID on the forums, it is usually met with an immediate advisement for removal. This photo, used with permission, by Daniel Knop proves that there is indeed some risk. There is no debate, that’s a coral and that’s a starfish wrapping it’s stomach around the coral, leaving a trail of death in its wake. It sounds like I’ve been watching too much Game of Thrones.
Although this picture proves they can eat coral, the more important question is how likely is it they will eat coral. I think the risk is minimal and it’s why more pictures like this don’t exist. Some people try to ID by sight alone which will eat coral and which will not, yet these criteria have proved to be unreliable. What seems to be fine in one person’s tank is reportedly chowing on corals in another. So, is it species related? Environment related? Overpopulation related? Who knows.
I too have jumped the “Score!” team and would remove them in any tank where I wanted coralline. They’ll make your nice purple rock look like it has chicken pox. So, for a purely aesthetic reason and despite my love of biodiversity, I have joined team “Watch them!”.
There is not a complicated process involved in removing these guys. The most effective method is good ole elbow grease and early removal. If you see their numbers climbing, perhaps deal with it then. You just have to reach in and pull them out. The other method of removal is to buy a Harlequin Shrimp. These guys eat starfish, yet remember they ONLY eat starfish. Once your starfish are gone, you’ll need to decide if you want to culture your own, buy larger starfish, or perhaps you want to rehome him to another tank overrun with starfish.
Here’s an interesting thread on REEF2REEF to learn more about these little guys.