So you think you know fish? I need your help

[Surfacer]

I woke up this morning to find a little 4.5" surprise in my sump. I do not know what kind of fish it is, but I would like to know what you guys think.

Is it a baby fish of some sort?
Is it good or bad?
Anything else you may know based on looks alone?

I have a 180g tank with a Emperor Angelfish and Picasso clown. I have had the live rock for about 4 years and have not added anything to the tank for about 1 year. I will add pictures but they were taken with my iphone. I will try to get better pictures later when I get a much better camera, but in the mean time can anyone help ID this fish?

 

[rssjsb]

Do you have a sea cucumber in your tank? That looks like a pearlfish.

 

[philter4]

I am pretty sure it is a pearlfish and not all of them live in sea cucumbers. In all pearlfish there is a small appendage just in front of the dorsal fin and it is hard to see but in the first photo, just about 1/2 way down the back you can see the thin yellowing "thing" sticking up with a bulge in the middle, if this is part of the fish that is what it is, if this is my imagination I still think it is a non sea cucumber living species that was just in the live rock for all of this time.

 

[rssjsb]

Interesting - I always learn something when you're around.

I had no idea there were non-symbiotic pearlfish, but it makes sense that there are different varieties adapted to different conditions. Are they endemic to a particular region?

 

[Surfacer]

I apologize I was not able to get better pictures. After researching a bit on what you guys said I agree with the pearlfish ID. I am not sure what kind this one is, but I do have two sea cucumbers. I have one Spiny Sea Cucumber (Pentacta anceps) and one Tiger tail (Holothuria hilla) I believe.
I placed the pearlfish back into the display next to the cucumbers. After researching more I read many sources stating it is unsure of whether or not the pearlfish is a parasite fish but that it causes no harm.

Thank you for the quick responses. If there is any more information about them or anyone else has them in their tanks I would be interested to know about it.

 

[Daniel Reef]

Just watched this video about a pearlfish re-entering a sea cucumber.

http://www.youtube.com/watch?feature=player_embedded&v=Fw2DrbhOA-M

 

[philter4]

I placed the pearlfish back into the display next to the cucumbers. After researching more I read many sources stating it is unsure of whether or not the pearlfish is a parasite fish but that it causes no harm.

Thank you for the quick responses. If there is any more information about them or anyone else has them in their tanks I would be interested to know about it.

I have some sources that say it depends on the species as to which species are parasites and which are just commensalistic symbiosis, where the pearl fish benefits but does no harm to the sea cucumber. Mainly it depends on the species but even in the parasitic species it usually does no harm to a healthy cucumber.

I had no idea there were non-symbiotic pearlfish, but it makes sense that there are different varieties adapted to different conditions. Are they endemic to a particular region?

There are no non-symbiotic pearlfish that I am aware of but not all of them use sea cucumbers as hosts, I have read of at least one species that uses a muscle and another that uses a tunicate but these are so rare they would probably never be encountered by aquarists and I doubt they would even be introduced into an aquarium let alone survive since neither host is able to be kept in aquariums long term.

 

[G4546]

Great thread, similar to what rssjsb said definately learned something new! Thank you. Quite interesting, this duo here..

 

[Surfacer]

philter4, thank you for all the information you have provided as well as everyone else. It is really interesting to learn about these type of relationships and even more so in a home aquarium.

Since there are not too many videos out there, here is a top down video I captured of the Pearlfish I found. Again sorry I could not provide better quality but I thought it was still quite interesting to watch. Enjoy

http://youtu.be/7EgUhuPPg2Q

 

[CM67]

We had Pearlfish emerge from a piece of Xmas Tree Worm Rock at a LFS where I worked about 6 years ago.First and only time I have ever seen them not with a cucumber.The "rock" was a football sized piece of Porites covered with about 30-40 Spirobranchus giganteus.

Cheers
Craig

 

[Shells4]

Wow you learn something new everyday. Very interesting and gross at the same time.

 

[KafudaFish]

Hey this isn't the lounge.


Backs away slowly.

 

[wrasse123]

weird freaky looking thing. how cool!

 

[R_Hudson]

The Buttfish. Beautiful little speciman. It is very fascinating how they form this kind of relationship with cucumbers.

 

[Misled]

I don't know, I'd want a full mopp suit before going in.