Jellyfish after water change?

[WARz]

Can anyone tell me exactly what this is and if I need to worry? A dozen or so showed up in my tank. I got one in a glass to get a good video, they are very small.

 

[flsalty]

Medusa hydroids. I wouldn't worry too much. They usually disappear on their own.

 

[WARz]

Thanks, would they have come from the salt mix?

 

[Crabs McJones]

More than likely came in on a frag plug or live rock. But I do agree with the ID above

 

[flsalty]

I suppose anything is possible but I'd say probably not. How old is the tank? Most likely came in on a frag or live rock.

 

[WARz]

Tank is 5 months, only have a few hermits, a couple emeralds, no fish in this one yet, two candy canes, two flower pots, xenia and colony of zoanthids. Everything is groaning great. No corals added for over a month. These showed up after water change with new batch of IO RC. Probably was on plug with zoanthids. Last thing added.

 

[steves]

They just come in randomly sometimes. No one really knows. NO problem though.