Planaria are those white or pinkish filamentous things you can see on the sides of the aquarium. These are nocturnal flatworms, classified under Phylum Platyhelminthes. Some would mistake them for algae, but these are actually non-parasitic white worms that can thrive in tank conditions where fish is continuously overfed.
These thread-like worms don’t really pose an imminent danger for your fish, however their presence is a warning sign that you have been overfeeding your fish and there is excess food and waste in the bottom of the aquarium. The accumulated food provides an excellent environment for the Planaria to thrive in. Most outbreaks occur in improperly-cleaned aquariums. This is especially true when you have carnivore fish whose digestive systems are not quite efficient and tend to let a large portion of the nutrients pass through their digestive tract unabsorbed.
Although Planaria won’t harm your fish, their presence will tell you that the existing conditions in your tank are becoming unfavorable for the fish population, and if these water parameters are not recognized and corrected, the results may be potentially fatal for your fish and other tank inhabitants.
When there is excess food, decomposition results in a consequent spike in ammonia levels which can be deadly. If the tank’s bacterial filter is able to sufficiently deal with the ammonia spikes, you will be able to notice increasing levels of nitrate in the water. Although nitrate may not be as dangerous as ammonia, it is still a hazardous chemical that should be eliminated or it will eventually cause mortality in your fish population.
To successfully eliminate these worms from your aquarium, you have to remove their source of food.
Here is a step-by-step procedure on how to get rid of Planaria:
1. Thoroughly vacuum the tank gravel and/or substrate.
2. Do a partial water change (30-50%). You can also stir the gravel daily until all the excess food and waste materials pass through the tank’s mechanical filter.
3. Partial water changes should be done weekly until all the water parameters are within a suitable range.
4. You can choose to remove the worms if you really want them out of your tank fast. This is recommended when you are breeding fish, since Planaria will eat fish eggs. Fish will also feed on the worms, and the remainder will eventually die when their source of food is removed from the tank.
Another method practiced by some hobbyists is to put some shredded beef inside a gauze bag. The bag is hung among the tank’s plants, near the bottom. Since Planaria can easily be attracted by the scent of meat, they will converge on the gauze bag. After several hours, carefully insert a cup or bowl of water under the bag, and remove the bag from the tank. Putting in bait traps can be repeated for several days until Planaria is eliminated.
Other methods of eradicating Planaria from the fish tank include putting in macropodus fish. A chemical method is sometimes used by making an ammonium nitrate solution (concentration: 0.6-0.8 grams per 100 liters water).
About the Author:
Peter Hartono is the founder and CEO of Just Aquatic – a proud Australian company that provides excellent online aquarium supplies for hobbyists to build their own betta fish tanks and freshwater shrimp tanks.