What Are These?

[Alex Brown]

Hi, im very new to fish keeping, I set up my tank about 2 weeks ago. Right now its just live rock, with one hitch hiking crab and a few unidentified plants. A britle starfish also creaped out along with a few snails.

Can anyone tell me what these could be?

I also have very tiny, white/blue see through shrimps, these arnt mantis are they? I would say the largest one I have found is under 1cm long.

My live rock came from 3 different sources.

 

[Jonny967]

Aiptasia anemones!, you need to get them out of there as they will harm corals (if you are wanting corals of course) buy some 'joes juice' and squirt them with it. It has worked on every aiptasia i had within a minute.
If you leave them they will bread and take over the tank. Also do not physicaly remove them as parts can break off and spread.

 

[Donya]

Looks like a bunch of Aiptasia as Jonny said, but that last one isn't the same. Perhaps a Mojano amenone? Although I actually find both to be pretty when in the right circumstances, both can over-run a tank very easily and damage some corals they get into turf wars with. How much of a threat they are to corals depends on species for the Aiptasia. I've left various Aiptasia species have the run of a non-coral couple tanks in the past though and they did amazing work as living filters. So, these nems aren't always bad in all tanks, but they can cause you a lot of grief if you aren't content to have jillions of them in the near future.

The main issue is whether you'll be putting corals in (gotta get rid of the Aips and Mojano for sure if you go that rout), and whether you want to have them populate your tank. If you let the populations explode, you'll have a real job cut out for you trying to beat them back. Even the populations I deliberately let run wild in my tanks had to be cut back a little bit periodically to keep things in ballance.

 

[Alex Brown]

Thats great thanks for your help, however I was hoping the Mojano would be some sort of nice anemone!

To be honest, they are over running, I could count more than 20 I think. All are tiny, except 2 that I diagnosed as Aiptasia, they are over an inch long now (not photo'd).

Do red hermit crabs really eat these? I read some things on the net this morning. There are too many in there, I would rather let a crab eat them up then have to manually squirt them!

 

[Donya]

Nah, you won't find a hermit that will eat Aips or Mojanos. Peppermint shrimp will, sometimes, although I've read more accounts of them not doing such a great job at population control than I have full success stories.

however I was hoping the Mojano would be some sort of nice anemone!

Well, no nem has to be bad, and some Mojanos I've seen can be quite beautiful (the green ones especially). They just have a sting that will nuke sensitive corals and are impressively resilient compared to other anemones, hence their overpopulation potential. Mojanos would probably make an ideal anemone for a species pico or other tank that would be completely unsuitable to keep other anemones - they're just not an ideal thing to put in a community tank or one primarily for corals.