Do bristleworms kill, or just clean up

[kalmarrin]

Hi - four days ago my pearly jawfish left her home of two months, and seemed to get 'stuck' on the other side of the tank. It's like she was too afraid to go back to her home, or didn't know how to find it. I discovered a large turbo snail had sort of bulldosed the front of her hole and thought that it might have freaked her out. She eventually went back over to her hole, but wouldn't go in, staying, instead, near the glass for over an hour. She finally did go in, but the next morning she wasn't there. Having just found our little lawnmower blenny dead and headlness the day before, I was really concerned that something was freaking these den-dwellers out and possibly eating them. She reappeared the next day on the far side of the tank with a new, much improved hole with a at least three openings. I was much relieved. She came out and ate that morning and evening. Late that night, as I was watching TV, I heard some serious splashing. I looked up to see her flying all over the tank, at the surface...panting and totally panicked. Naturally, I took a flashlight and looked all around in her holes to see if something was in there with her. Couldn't find anything. It took her a couple of hours to calm down. She eventually went to the far side of her home and plastered herself up against the wall of the rock. The next morning she didn't come out to eat and when we looked in the hole, a bristleworm (by everyone's pictures and descriptions) was wrapped around her and had eaten her right down to the bone....she was virtually filet'd. I immediately took all of the corals from that piece of live rock, turned it upside down and tried to catch this thing that was just oblivious to the light or me or anything. He wanted to finish the meal he had started. Did this thing kill her...freak her out by nibbling at her?? Most of the threads on this forum say that are 'good guys'....but, I've mysteriously lost actually four fish now (all four were den dwellers) - that were otherwise very healthy and eating and such up until the lights came on in the morning. The one that was eating my pearl was about the size of a coffee stir in circumfrence...so not a big guy...and I have seen another one (the same day) that was a tiny bit bigger. Can't tell how long because the body stays in the rock. If they are good guys I'll leave them....but...something sure freaked her out. Do they nibble on these guys as they sleep? Thanks for your help. Do they need to go?

[Sloth]

Whenever somebody brings up the issue of bristleworms, I maintain that there are different types of bristleworms. Those that will kill fish and those that will not.

My first tank had a HUGE worm that killed (I believe) and ate my only fish. It was over 6", was olive green or brown, shiney, segmented, and had "spikes" instead of bristles. It also had 5 antennae sticking straight out from its face.

On the other hand, all my subsequent tanks have had a healthy population of "regular" bristleworms. I've had them get at least 6" in length too, but NEVER harm a fish, snail, clams, or anything. These are the ones that are pink/white with a shiney blue/green sheen to them. Their bristles are more hair-like and stick like fiberglass in your fingers.

So that's my anecdotal answer. What did your worm look like?

[kalmarrin]

It was about as big around as a coffee stir, mostly a brownish color...soft bodied with bristles sticking out from the sides. It's mouth was a round, gaping hole. He was seriously devouring my fish. She was sort of hung up in a mucous kind of webbing - possibly from one of my wrasses that had slept there - unless these worms make their own to sort of trap their pray. It was everywhere. He was very slick, tho - every time I got too close, he would just slink backwards into the rock.

[greenbean36191]

Here is a good article to read: http://reefkeeping.com/issues/2003-04/rs/index.htm

Basicly, the bristleworms we find in our tanks are scavengers, with the exception of one uncommon species, which eats soft corals. None of them have jaws, so unless your fish sits there and lets a worm lick a hole in it then they have nothing to fear from these worms. They also find their food by smell, so they don't even recognize live animals as food.
However, there are some other worms in our tanks that will eat fish. In Sloth's case it sounds like he had a eunicid worm, which are very different than what are normally called bristleworms. So when people claim that bristleworms are eating their fish and they go on a bristleworm hunt they are going after the wrong guy.

[Sloth]

Yeah, don't get the wrong idea about bristleworms. I used to hate them all, but just last night I saw one on my glass actually grazing on hair algae.

Greenbean- that sounds about right. I think I remember discovering that it was that type of worm.

[rshimek]

Hi,

Just as most reef aquarists seem to think that there is only one type of coral (see my article in this month's Reefkeeping Magazine), the also seem to think there is only one species of "bristle worm." Put in perspective, there are more species of so-called bristle worms than there are species of birds. Just as different species of birds do different things, different species of polychaete worms do different things. Take a look at this article for a bit of background.

The occupy every conceivable ecological niche in the sea.

In our tanks, scavenger worms are the most common ones. See this article for a discussion of those types, but also a discussion of a few of the predatory types that may show up from time to time.

There are, indeed, worms that will catch and eat fish. However, they will strike, kill, and swallow the WHOLE fish within a few seconds. If you saw the corpse of your fish being eaten by worms, these were the scavengers. They don't even have jaws... To get any flesh off the corpse they rub roughened patches of mouth epidermis back and forth over the dead meat. In effect, they "gum it" to pieces. This kind of animal simply can't catch or kill a live fish.

[capncapo]

I wonder if she couldn't have some cirolanid isopods taking care of her fish.if only the den dwellers seem to be affected. Could be the cause of her fish acting that way. Then after they're dead, the worms take over. Just a thought.

[rshimek]

Hi,

That is unlikely. Cirolanids are not burrow dwellers, they prey on fish in the water column. In fact, I suspect burrow dwelling fish may be largely immune to their predation.

The worms are cleaning up the carcasses, for sure, but what is killing the fish is open to question.