Black Spots on Live Rock

[Marcosreef]

I seem to be getting what appears as black 1 millimeter spot on my Fiji live rock and they seem to be spreading.

It's either eating through the coralline algae, or growing around it.

Anyone seen these or know of this?

Thanks, Marco

Note: See New Image Below.

 

[Len]

Hmmm. When you have the time, take a closer pic of them, with brighter exposure (set EV on camera a few steps higher). There's a big difference between "eating through" and "growing around" coralline (the former will produce divets). If you can, describe the texture of these spots (either via touch of sight). Hard? Soft? Slimy? etc. I'm also assuming these spots are non-motile.

I'm not sure I can help, but I'm willing to take a stab at it if you can provide more info.

 

[Marcosreef]

Here are some new pics:

In this picture, I scraped away at the top spot. It appears to be embedded into the live rock. I could not completely remove it after scraping away a few layers of coralline.

I have never seen anything like this. I piece is moderately covered.

Marco

 

[Len]

After discussing this with an unnamed individual , we going with: boring sponge of the genus Cliona.

 

[Marcosreef]

Thanks Len,
If I decided to get a clam, will this be a prob?

Marco

 

[Len]

I don't know. Boring sponges bore into clams for habitat, not nutrition. However, the effects of their boring can indirectly kill clams by opening up entry ways for such nasties as predatory organisms. I'd be particularly worried about small clams. Larger clams, with thicker shells, will probably fare ok even if bored into; Most of these sponges only penetrate fractions of an inch.

If you wish to eradicate them, it shouldn't be too hard. Sponges aren't particularly hardy, and are easily "influenced" by environmental pressures. Indivudally injecting these colonies with hot freshwater will probably do the trick (hot kalkwasswer if necessary). If it hasn't spread to every region of the tank, removing the infected rock may be all that is needed.

Keep in mind that I'm not sure what species you have, nor do I know if it will bore into Tridacna shells. These guys may be harmless or harmful. For all I know, it might not be even a Cliona. I wish I could tell you, but sponges aren't my forte.

Curious .... Do you have SPS in your tank, or other stonies? Have they shown any negative symptoms?

 

[Marcosreef]

Len,
I have 3 SPS frags: Acropora, Montipora Capricornus, and Pocillipora (Sp?).

Anyway, none has shown any symptoms as of yet, and are very healthy.

Regards, Marco

P.S. I wish you well on your new clams.