What are these things on my glass?

[gooicide]

I just set up a new tank and it is currently going through the cycle period. A few days ago I noticed these small, snowflake-shaped things growing on my glass, and they have multiplied quickly. There are no animals in the tank except for copepods and a few small isopods that came off the live rock. These things resemble small white anemones, a disc with several tentacles emanating from it, but they have no stalk. Sorry for the low quality of the picture, it's the best I could get. Are they some kind of egg case? Should I be concerned about these?

 

[Lionfish Lair]

They are hydroids. Medusae stage. You don't need to do anything. They'll go soon.

 

[gooicide]

They are hydroids. Medusae stage. You don't need to do anything. They'll go soon.

Okay, thanks.

 

[ahiggins]

Weird

They are hydroids. Medusae stage. You don't need to do anything. They'll go soon.

is that normal for cycling? I've always thought hydroids were the devil lol

 

[RobBaglieri]

My tank was loaded with them at one point when I first set up the tank. They just dissipated once I started using my lights.

 

[Lionfish Lair]

The medusae are harmless unless you have fry or something like Dwarf Seahorses. They are often seen with the cycle, yes. They can occur at other times if there's food available, but frequently seen in the newer tanks. They are very interesting to watch.

 

[ahiggins]

Interesting. I had one come in on a frag and I superglued it lol

 

[Lionfish Lair]

That's a different stage of the hydroid and people often remove them such as you did.

 

[gooicide]

Weird

is that normal for cycling? I've always thought hydroids were the devil lol

Now that I'm reading into it, I see some people saying they're harmless and some people saying they're the worst thing ever. These things are all over my glass. Their population must have doubled overnight.

 

[Lionfish Lair]

That's what they do. When you look around at research, take note if they are talking about "hydroids" or "medusae". They are actually totally different topics.... well not totally

 

[ahiggins]

That's what they do. When you look around at research, take note if they are talking about "hydroids" or "medusae". They are actually totally different topics.... well not totally

So medusae stage are harmless but if they dont die before they hit the hydroid stage, then they are an issue?

 

[Lionfish Lair]

I've never seen them turn into anything. It seems that stage doesn't do well in our tanks, not like you would think.

 

[ahiggins]

Interesting, good to know