New growth in reef tank- harmful?

ryansreefrocks · 2026-09-07T19:49:43-0400

Can anyone tell me what this is? It seems to be growing along the base of the zoanthid plug and now one of zoanthids is shrinking in. Please help! And thanks!

Subsea · 2026-09-07T23:26:43-0400

Ryan,
Use white light to help with identification. I do’t see anything, however, if you don’t like what you see, then take plug out and use tooth brush dipped in peroxide and brush the offender away.
You could give it a 10 minute bath in a 10% solution of 3% peroxide.

I see this is your first post. Welcome to r2r. Consider starting a tank journal in members tank forum.

Mr. Mojo Rising · 2026-09-08T07:10:39-0400

It does look like something is growing, but the picture is not clear enough to see clearly

RobertK · 2026-09-08T12:06:15-0400

It almost looks like cyphastrea or similar encrusting coral got onto that frag plug and is up onto the zoas. is it hard or soft? Can you remove it?

And welcome to Reef2Reef!

ryansreefrocks · 2026-09-08T18:38:10-0400

Subsea said:
Ryan,
Use white light to help with identification. I do’t see anything, however, if you don’t like what you see, then take plug out and use tooth brush dipped in peroxide and brush the offender away.
You could give it a 10 minute bath in a 10% solution of 3% peroxide.

I see this is your first post. Welcome to r2r. Consider starting a tank journal in members tank forum.

ryansreefrocks said:
Can anyone tell me what this is? It seems to be growing along the base of the zoanthid plug and now one of zoanthids is shrinking in. Please help! And thanks!

Mr. Mojo Rising said:
It does look like something is growing, but the picture is not clear enough to see clearly

RobertK said:
It almost looks like cyphastrea or similar encrusting coral got onto that frag plug and is up onto the zoas. is it hard or soft? Can you remove it?

And welcome to Reef2Reef!

Mr. Mojo Rising · 2026-09-08T18:55:42-0400

I'm guessing hydroids, but I'm not sure, whatever it is I don't think its good. Just my 2 cents but I would toss that frag before it spreads onto the rocks. Better safe than sorry IMO

RobertK · 2026-09-08T19:00:46-0400

Is it hard or soft?

If it is hard it looks like an encrusting coral to me, which you might be able to gently peel off the zoa mat. You could also cut off the portion of the frag plug where it is hanging over the edge and glue it to another frag plug - free coral!

But if it is soft I might be wrong and Mr. Mojo could be right!