Baby starfish everywhere! Good? Bad?

S

simontan

There was a recent boom of baby starfish in my tank, and I was wondering if there's any reason for concern or if they will mostly die off or get eaten eventurally. I have 2 or 3 large brittle stars now and 1 very large green brittle star. There are probably 2 or 3 dozen babies all over the place. They started showing up about 2 mos. ago and are about 3/8" now. I assume they're babies of the brittles, but they don't look anything like them right now. They are white with either 5 or 6 fat arms. I'll post some pics later - I wish I'd taken some earlier when one was hitching a ride on a hermit crab, and it looked like the crab had a Cowboys helmet on :lol: .
 
Sounds like an asterina star. Some claim they eat corals, but we know that they also eat algae. You might want to reconsider the green serpent star, too. If you get a pic, we can confirm, but the green brittle stars are known fish eaters.
 
as long as the green brittle star doesnt get to big it shouldnt be a problem. I had one in my 125 I used to have and her never bothered any of my fish. I kept him well fed though with chunks of meat.
 
Here's a pic of couple of them clinging to the overflow. Don't know how to take good close-ups with my camera otherwise I could get the underside of some stuck on the glass. Also, I guess I was mistaken when I thought some had 5 arms. Looks like they all have 7 arms.
 
Yeah they look like asterina stars. I am of the opinion that there are good ones and bad ones.

I have personally seen asterinas eat coraline algea and I have seen some latch on to the stalk of my zoas (unsure if they were eating or laying at this time) It seems like if they are pure white, they are benign; if they are grayish or darker they may have a different agenda.

I just picked one off about an hour ago that was covering the head of one of the polyps of one of my zoa colonies. It still has not opened up.
 
Unfortunately, color, size and number of arms are not diagnostic. There are many species of Asterina, and even seastar experts can not identify them easily.

There is no doubt that there is a bad species or two in the hobby.

But the overwhelming majority are harmless. They will not suddenly become problems, either - at least in terms of suddenly starting to eat corals. They either are coral eaters, or not. Mostly they will be on rocks and glass, eating surface biofilms. They will be drawn to dead or dying corals long before we know there is a problem.

But most people have no problems with them at all. Some can make a dent in coralline algae but often this is not a major issue. This is the most common complaint. It is rare to find a coral eater, but there are SPS as well as soft coral predators around.

Keep a close eye on them, but I generally consider them beneficial in most cases.

If you have a sudden "bloom" then I would reconsider your feeding and or stocking rate, as they often increase in numbers due to increase in available nutrients.
 
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