Bad Type Bristleworms and Fireworm Control in Saltwater Aquariums

Introduction

Fire bristleworm up-close

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The name "bristleworm" is a label loosely applied to describe all Polychaete class marine worms, but it is members of the Fireworms Amphinomidae family that have earned the name of being what most aquarists consider to be "true" bristleworms.

Primarily it is the Pherecardia (Pacific), Hermodice (Caribbean), and other related species that one needs to be concerned about. These Fireworms are errant (roving) carnivores that can cause much damage in a reef tank. They have toxic bristles on their bodies that can inflict a sting of a very painful degree, possess strong jaws for feeding, and can reproduce quite rapidly.

They are not selective about what they eat but usually prey on all types of other motile (moving) and sessile (attached or stationary) invertebrates, such as corals, crustaceans, mollusks, sedentary type as well as other errant type bristleworms. Being particularly aggressive predators, they may even eat small fishes, if an opportunity presents itself. For these reasons preventing these destructive worms from accidentally getting into, or removing them when found in a saltwater aquarium system is recommended.

Fireworms are typically introduced into an aquarium by hitchhiking in on live rock, so taking the time to inspect all new pieces of live rock for these animals before placing it into your aquarium is the first step in preventing an infestation. By laying the rock out on newspaper, a sheet of plastic or linen, if any of these worms are present, you will see them sticking out of or crawling around on the rock. Take tweezers and carefully grab the worm as close to the base of the body as you can see sticking out, then gently wiggle and pull it out.

  • Tip: It is advised always to wear a pair of gloves of some kind when dealing with Fireworms to avoid coming into contact with their stinging bristles.

Simple Removal Methods

  • Remove them by hand using tweezers or a net when you see them.
  • Buy a bristleworm trap, or make your own.
  • Use a baited nylon stocking.
  • Introduce a natural predator of these worms into the aquarium, such as a Dottyback, Wrasse of the Halichoeres family, Bird Wrasse (Gomphosus varius), Maori Wrasse (Cheilinus oxycephalus), Sunset Wrasse (Thalassoma lutescens), Coral Banded Shrimp (Stenopus hispidus) or Arrow Crab (Stenorhynchus setrcornis). Although the last option is very popular, caution is advised. An introduced predator will eat the bad worms, but species such as these will eat other types of desirable inverts and crustaceans as well.

Severe Infestation Solution

Although this problem is not likely to occur if the worms are removed when found, if your aquarium is overwhelmed by a severe bad type, or even a beneficial type bristleworms infestation, such as with those of the Eurythoe genus, you can quickly reduce the population by cleaning up the substrate and rocks. Here is what you can do.

  • Only remove small portions of the aquarium substrate at a time and either:
  • Spread it out on a plastic sheet, then sieve through the media by hand and pick the worms out using tweezers.
  • Place the substrate in a plastic container partially filled with saltwater, and stir it around. The worms should come up from the media each time this is done and be in the water portion of the container where they can be scooped out. A fine-meshed fishnet works well for this.
  • Remove the rocks one at a time and follow the rock cleaning procedure outlined under the "Preventative Measures" section above.
  • Whenever working with live substrate media and rocks in the open air, it is best to keep it moist, which can be done by using a spray bottle filled with salt water to dampen it.