Speed-swimming worm?

[psa]

A few nights ago my wife came in to ask me if there was a new fish in the tank. I said no...why do you ask?

There was a critter of some sort swimming through the tank extremely fast, zipping back and forth at about four feet per second. We watched him swim laps around the tank for a bit and finally I grabbed a net and a glass of tank water and snatched him out. He moved so fast he went straight into the net, once I was lucky enough to guess which way he was going to go next.

What I pulled out looked like a worm, a little over an inch long and still moving rapidly around the glass. I managed to snag these pictures of him, but have not returned him to the tank on the theory that he's just as likely to be damaging to the tank as beneficial and he had managed to hide pretty well up until he decided to swim about in the open water like a maniac. I will also point out that the only thing added to this tank in the last month was a kole tang (the only fish) and it died the day we found this. This thing showed up within five minutes of my removing the dead fish.

 

[jesshimom]

I knew there was another reason to always wear gloves when dinking around in your tank. That would make me run far far away. I can't wait to hear what that freaky thing is.

 

[nasher8860]

Wowo never even seen anything like that before....also very interested. Cool you were able to catch it easily.

 

[Curtswearing]

Based on the pic, it's most likely an epitoke. When most polychaetes (bristleworms) need to reproduce, a portion of their body starts changing. Eventually this portion of their body breaks off and does the whole "spazz-swimming" thing before they dissolve releasing gametes.

Most people have never witnessed this because it typically happens when the lights are out...consider yourself lucky. It wasn't harmful but you also did not harm your reef by removing it.

The other possibility is a pearl fish. If you had a cucumber die recently this is a possibility. I'll let you do your own research on that issue.

 

[FishinInTheDark]

I would agree with the sexual bristleworm ID (epitoke). I can't believe you caught that thing! I saw one once in my tank and it was so dang fast, zipping around like it was on crack!

 

[Skimmy]

creepy!!! never seen one and im glad. it does kinda look like a mutant bristle worm.
put it under your wifes pillow