Two sets of hitchhikers

[aquaddict]

Hello all,
I believe I have a family of very tiny fish (not pods, as I thought). They are currently a half-centimeter (some smaller-"mm" sized), slender and tan transparent colored. They appeared with some plant rock from the LFS and make their home in a cave area of the live rock. Does anyone know about them?

Secondly, there are a group of tiny brown stems emerging from that same live rock (Indo-Pacific) with brown-reddish crowns/tentacles?. Could they be aiptasia, tubeworms or hydroids (1/2 centimeter in size, at the largest).
Thank you.

 

[Anonymous]

Well sounds like you have mysid shrimp, and hydroids. The hydroids can be a pain, they like to "take over" and invade tanks. Mysid shrimp are great though! Little hard to dip in cocktail sauce, but tasty none the less.

 

[Len]

The first is very hard to ID. Mysid Shrimps is a possiblity, or juvenile meroplantonic fish is a remote possiblity too. You'd have to let time tell what they grow up to be, if they do reach maturation.

The second critter does sound like the pesky hydroids or Aiptasia. They could also be a more beneign species of other polyps (although these can grow to plague-like proportions as well). The safest thing to do is to isolate the rock so it isn't adjacent to the rest of your other rocks. In case this thing spreads like weeds, you can remove the rock entirely.

 

[Anonymous]

Here is a link to some fine fix of Mysid/Mysis scrrrrimps. Is this what you see in your aquarium?

http://www.seahorse.org/gallery/album91

 

[aquaddict]

Hello,
I think my small "hydroids" are feather dusters, because they did withdraw into the hole after being disturbed.

As for the mysid shrimp, they don't look like that, but they've been around for three weeks and don't look any larger.
Thank you all for your responses. Much appreciated