Urchin vs. Brittle star?

[Tango2]

So I've recently added an urchin to my tank to battle a never-ending battle with bubble algae (as seen in below pics). He's been in the tank for about 5 days now. I noticed him losing a spine or two, but otherwise seemed fine, and wrote it off to acclimation/stress. Today I came home to find the urchin spineless with my brittle star in an odd location with a piece of tentacle missing next to the urchin. Only about 2 inches or so of the star, so I think he will likely recover. Not so sure on the urchin.

I hate having any loss in my tank, but from what I can tell, this may have been out of my control. Has anyone seen this behavior before? Could I have done something to cause this or was it just bad luck? I've had plenty of this already (see bubble algae in pic below!)

 

[Tahoe61]

I would do a water chemistry check asap.

Urchins loose spines and die (no recovery) secondary to less than ideal water conditions. As far as I know Urchins do not eat bubble algae, where did you see that Urchins were a solution to bubble algae, I could be wrong.

 

[Tango2]

I've read that in several places that they will eat everything down to the rock, but it doesn't seem to be agreed upon widely. After researching, it seemed like a viable option with some added diversity to the tank, even if it didn't eat BA.

 

[Tahoe61]

Oh I use Urchins to clean up algae routinely and then pass them on once the algae issue is resolved.

Urchin will not tolerated swings or less then ideal water chemistry, they loose spines first, and if the issue is not resolved die shortly after loosing spines.

My personal preference for Bubble Algae removal is the true Emerald Crab. Some have had issues with the Emerald, I have not.

 

[Tango2]

I added several more of them, and along with manual removal I'm determined to beat this. It's just strange that the urchin and star are next to each other like they had it out with each other.

 

[DeniseAndy]

Never seen my red large brittle go anywhere near my urchins. Maybe the urchin died and the star was cleaning up. Although the loss of tentacle could be bad too. Definitely check water for any swings or issues.

Also, none of my urchins really eat bubble algae. Only thing I have used is Rabbitfish. However, you must have a system large enough and no lps for them to then eat. I have emeralds, so maybe they help too.

 

[Tahoe61]

The Star probably could detect the odor of decay from the Urchin and was attracted.

 

[Tango2]

That is very possible on the decay. This all happened today between the time I left for work and my return. To make matters worse, I'm currently in the middle of a renovation in my house that I'm sure is adding to any potential stress. I'm currently running sumpless with my mp10 providing the circulation for the tank. I hope to have everything back to normal by the weekend, but will be checking parameters shortly to see if anything is out of wack

 

[Tango2]

Update: checked salinity, ammonia, nitrate, nitrite. All measured great (1.026, .25, 0, 0). Only thing I don't have a good indication of is ph, as my probe has been out of whack for a while, and I have one on order to install in my new sump when I get it finished. With the change in circulation, maybe that caused a ph swing?

I plan to continue monitoring, but parameters look good.

 

[Tahoe61]

If you're using a hydrometer I would double check the Sg against another test method. Sudden changes in pH can adversely affect sensitive inverts, but you would have to had added something to the tank like a buffer or other chemical. Are you dosing the tank? The Urchin could have just been a compromised specimen, if not than water chemistry if your culprit.

 

[Tango2]

I'm not currently dosing anything, and I'll give my hydrometer a check to see if it is reading accurately. I just calibrated it recently, but who knows. Maybe just compromised like you said.

 

[tj w]

Why do u have an ammonia reading in your tank? Is it fairly new? If not, u need to get this checked on. If your tank is done cycling your ammonia should be at 0.

 

[Tango2]

I did have a dead urchin in the tank. I'm attributing that to the ammonia levels. Tanks is 2.5 years old.

 

[Triggreef]

No way a dead urchin would contribute to ammonia in a 45g 2yr old tank. . At least imo. There's almost nothing to those. I agree the star was probably next to it looking to clean it up.

+1 emerald crabs for bubble algae. And all other algae. Have to have them in numbers though. Like 10 for a 45g tank. I added 15 to my established quarantine 72g infested with bubble algae. Its made a dent but I'm about to add 15 more. Took some before pics this time to back up my claims.