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Bristle Worms - The Shocking Truth - What You Need To Know

Author: Sammie C.

What Are Bristle Worms?

Aquarists know them as Bristle worms, but scientists will talk about Polychaeta or polychaetes. The marine worm falls under the paraphyletic class of Annelida worms.

If you are running saltwater reef tanks or aquariums, then you likely have this type of worm. The Bristle worm is a nocturnal critter which loves to spend most of its life in the dark areas of an aquarium. If you find them in your saltwater fish tank probably, they hitchhiked their way through the reef rocks.

Just like plankton, the bristle worms can be found in the coldest regions and also in Hydrothermal vents. Some are believed to live in the deepest depths in the ocean, such as the Challenger Deep. The marine worms are widely spread in the world’s Brackish waters, seawater or fresh water.

In appearance, the bristle worm has a segmented body, and each segment holds a pair of parapodia, fleshy leg-like parts, and a bunch of chaetae, hair-like bristles. Just like earthworms, they are cylindrical, but their characteristics are different from the other annelids.

Compared to fireworms, Bristle worms are thinner and pinkish. Their size ranges from between 3 and 8 inches. Based on the characteristics, there are two types of bristle worms, sedentary and errant worms. The sedentary bristle worms swim and crawl around using their parapodia, while the errant ones do not move around easily.

Do You Need Bristle Worms?

The moment this question pops up in your mind, you must have become suspicious about the population of these bristle worms in your in-fish tank. The increase in the number of polychaetes should or should not worry you much. But there is no doubt that you are also asking yourself, “should these worms be in your fish tank?”

The polychaetes are believed to be saltwater scavengers and Detritivores: they do the work of removing the dead bodies and decaying matter in the fish tank. Also, the increase of bristle worms in your tank is an indication of a bigger problem: the presence of a large amount of left-over food and dead animals or rotting in your tank. You can call them the voluntary tank cleanup crew or agent. Unfortunately, this part of their services to the reef tank goes unnoticed.

Are Bristle Worms Dangerous?

Due to the appearance of the bristle worms, you are likely to be asking yourself, “are they dangerous?” The answer to this question to a greater extent depends on the type of polychaetes species. The regular old polychaetes can only sting you if you happen to touch the bristles with your bare hands. However, there are other species in this class that are rare but very dangerous.

The fireworm is one of the most notorious errant bristle worms and a nightmare to most aquarists. The hollow bristles on this worm contain toxins and can break off easily. Making contact with the fireworm bristles can prick you and inflict intense burning pain on your skin.

The Amphinomidae family hosts some species of bristle worms that have venomous cocktails which can be used to attack your fish. These types of worms are considered to be carnivores and pose a clear threat to your tank.

Understanding the many species under the Annelida class will help you differentiate the good from the bad. Most of the bad worms have distinct features in terms of size and color, which make them easy to find and remove. The class Annelida has over 8,000 worm species, and good news for you is that there are 120 confirmed fireworms species.

Should You Keep Bristle Worms?

From a reef aquarists’ perspective, You should keep the polychaetes mainly because of their scavenging characteristic. They are good fish tank cleaners since they feed on detritus in your tanks such as dead decaying matter, and leftover food. If you are looking for a cleaning crew that can get into places, other organisms cannot then look no further.

If you did not pay to have the bristle worms in your tank, then that is a bonus. You can also pay to get the good worms and still maintain a conducive fish tank environment, but this option is rare and unusual because bristle worms show up. Furthermore, bad bristle worms are rare.

How To Remove Bad And Excess Bristle Worms

Bristle worms are suited to fish tank life, should you want to remove them, then you have three ways to do so. First, you can remove them using natural predators. Using natural predators is the safest way to control an organism’s population in your fish tank. Some of the bristle worm predators include Coral Banded Shrimp, butterflyfish, pufferfish, hawkfish, Arrow Crabs, Wrasses, and Dottybacks.

If you are opposed to using natural predators, then you have another option of using Bristle Worm Traps. Traps that have one way in and no-way-out approach offer the most effective solution. You can buy the traps, or you make one yourself using a plastic bottle container and glue.

By using a DIY bristle worm trap, you aim to entice them to fall into the bottle container trap, which gets buried at the bottom of the sand. You can easily place some food inside the trap. The downside of the trap is the size of the worm you want to catch. A commercial trap designed to catch small worms won’t serve the purpose of catching larger fireworm species.

The last removal option would be to remove the bristle worms by hand using a pair of tweezers or wearing special gloves to avoid the prick. This method is slow and may consume more of your time. Since the polychaetes are nocturnal worms, the best time to remove them is at night, when the lights are out.

New fish keepers can benefit from the best approach, which is always prevention. Evaluating the rocks that you put in your tank ensures that you have the right living organisms. From a reef aquarists’ perspective, you need a control tank for the rocks to help you identify the living things hiding inside.