Help - need identification

[reefjonny]

I've had this tank running for a few years and just noticed this star fish on the glass this morning. What is this and is it good / bad or no big deal either way.

Looking for some help?

Thanks,
ReefJonny

 

[StlSalt]

Asterina star. Tons of info on them now that you know what they are. Not bad, sorta good(CUC), they grow fast and can become a nuisance because of their sheer numbers.

 

[Zoa_Fanatic]

I agree with asterina star. They are the devil, they eat soft coral. Some people say they don’t but ime there are two varieties. If the back side of that thing has ANY color on it (I mean if it’s not white as the snow outside) kill it and every other one you find. The dark ones have eaten my Zoa EVERY time I’ve seen them. My LFS on the other hand has white ones that bother nothing. It’s taken me years to eradicate the colored ones from my tank.

First pic is the kind I know eat softies. Second is the supposedly safe variety. Also note I had some that were red on the back and even some that changed colors to match the rock. If it’s not solid white it must die.

 

[reefjonny]

thank you for the information, I believe they are solid white. I have only seen one and he was gone before I had any responses. I will say that the only corals I've lost have been zoas. I also had an emerald crab who I believe ate them during the night.

I'll keep an eye out looking for them...any idea how they would have made into my aquarium in the first place?

 

[Zoa_Fanatic]

thank you for the information, I believe they are solid white. I have only seen one and he was gone before I had any responses. I will say that the only corals I've lost have been zoas. I also had an emerald crab who I believe ate them during the night.

I'll keep an eye out looking for them...any idea how they would have made into my aquarium in the first place?

They come in as hitchhikers. HIGHLY unlikely your emerald ate the zoa. I’m guessing it’s these dudes. You’ll see one but there’s actually way more. They reproduce by budding or when one get damaged like getting an arm torn off

 

[Sump Crab]

I agree with asterina star. They are the devil, they eat soft coral. Some people say they don’t but ime there are two varieties. If the back side of that thing has ANY color on it (I mean if it’s not white as the snow outside) kill it and every other one you find. The dark ones have eaten my Zoa EVERY time I’ve seen them. My LFS on the other hand has white ones that bother nothing. It’s taken me years to eradicate the colored ones from my tank.

First pic is the kind I know eat softies. Second is the supposedly safe variety. Also note I had some that were red on the back and even some that changed colors to match the rock. If it’s not solid white it must die.

I have the "bad" asterinas in my tank and they are harmless. They will cover up zoas that are about to die but I am unsure if they are eating the algae on the zoa or if they are consuming some sort of necrotic flesh. They never touch anything healthy in my experience. I've had these guys for over 10 years.

 

[Sump Crab]

They come in as hitchhikers. HIGHLY unlikely your emerald ate the zoa. I’m guessing it’s these dudes. You’ll see one but there’s actually way more. They reproduce by budding or when one get damaged like getting an arm torn off

I have had an emerald crab who took a liking to acans however in most cases an emerald eating coral is probably due to the fact that the coral is dead or dieing.

 

[Zoa_Fanatic]

I have the "bad" asterinas in my tank and they are harmless. They will cover up zoas that are about to die but I am unsure if they are eating the algae on the zoa or if they are consuming some sort of necrotic flesh. They never touch anything healthy in my experience. I've had these guys for over 10 years.

Like I said it’s totally based on personal experience. I watched them eat an entire colony of dragonseye zoa that had been fine for years in my biocube before these dudes showed up. They would sit on top of a polyp and if I pulled them off often only part of the polyp would be left. It’s possible I just got bad ones but you can google it. Tons of people have watched them eat zoas. I wouldn’t risk if. I’ve spent years, YEARS, eradicating them.

 

[Sump Crab]

Like I said it’s totally based on personal experience. I watched them eat an entire colony of dragonseye zoa that had been fine for years in my biocube before these dudes showed up. They would sit on top of a polyp and if I pulled them off often only part of the polyp would be left. It’s possible I just got bad ones but you can google it. Tons of people have watched them eat zoas. I wouldn’t risk if. I’ve spent years, YEARS, eradicating them.

I must be lucky then

 

[Zoa_Fanatic]

I must be lucky then

I wish I could get ones like yours. I just don’t trust them anymore. I got mine from my brothers tank and they didn’t mess with his LPS but they loved my zoas