Unknown hitchhiker

[Imbarrie]

I have something living in the inner most crevices of a large piece of Fiji rock. I have had this piece for almost two years and only glimpsed this creature twice and I spend a lot of time looking at night with red and white LED flashlights.
This is what I have seen so far;
It is dark grey with thin light grey stripes and small densely packed square pattern of brownish color. It moves within rocks like a snail moves but it can't have a shell the places this goes. It also moves very slowly and is very light averse.
It has been living for almost two years in my tank yet hasn't eaten my pistol shrimp, cleaner shrimp or even my sexy shrimp. I haven't noticed any fish disappear, yellow watchman goby, clownfish or algae blenny. I do seem to loose margarita snails about a dozen per year but not my nassarius or my fighting conchs.
It is a complete mystery to me but I'm concerned if this dies will it crash my tank.

 

[ed4]

This is a long shot, but does it look anything like this?

I used to have these in my old tank, in the rockwork that I carried over into my new tank. These flatworms take out molluscs (clams, snails, etc.).

 

[Imbarrie]

I think that is exactly what I have.
Nice call.

 

[ed4]

I have my moments

 

[Imbarrie]

What is it called? All the websites I found spend most of the time showing small flatworms.

 

[ed4]

I'l look it up in one of my books, when I get home. I can't seem to find the name of this polyclad from a quick search.

Back when these things were in my tank, they decimated my Stomatella population, as I'd often find lots of their flat shells on the sandbed. They also took out some of my "paid" snails too.

I was able to syphon these out by using a silicone air line, even off rocks.

 

[daaznmofo]

go hunting at night or early morning before the lights are on

 

[Imbarrie]

I do spend a lot of time looking at night. Without a doubt, I spend more time looking at my tank with a flashlight given the hours I work.

I did find a lot of websites for polyclad flatworms and that is exactly what I have. Now Im wondering how to remove it. I will probably have to isolate that rock during a tank upgrade. Hopefully I will be doing that soon.

I did have a very healthy population of stromatellas and I thought my cleaner shrimp was picking at them. I want to get this thing out now that I have an idea of what it is. I loved those stroms.

 

[ed4]

Good luck and happy hunting.

From my past experience, I was able to find one of these (approximately) every 2 weeks for a total of about 10 flatworms. It seemed that I had better success if I spontaneously checked when the room has been completely dark for a hot minute.

I kept an airline and a small bucket handy, in case I found one.