Have you noticed white or clear slime growing on your aquarium? If so, you may be dealing with aquarium slime disease.
Slime disease is a catch-all term for the parasitic infections of the skin that cause freshwater fish to produce excess mucus. This disease weakens fish and makes them more susceptible to other, often fatal, illnesses.
But don’t worry! In this article, I’ll cover the most common causes of aquarium slime disease and some simple steps you can take to treat and prevent it.
How To Identify Slime Disease
Aquarium fish with increased mucus production will have visible cloudy patches on their skin and more mucus around their gills. This can cause difficulty breathing, which will present as heavy or labored breathing.
In addition, aquarium fish scratch their skin against solid objects when it becomes irritated. Plus, they lose energy and interest in food as they become more stressed. In severe cases, they will experience physical damage to the skin, leading to other secondary infections, like fin rot.
Marine fish usually contract slime disease from a different parasite, Brooklynella hostilis. It is sometimes called clownfish disease because it primarily affects them. When fish are stressed or exposed to toxins and irritants in the water (like copper), they produce more mucus.
Note: Some fish are always slimy (e.g., eels), while others only produce extra mucus during specific situations (e.g., right before parrotfish go to sleep).
Slime Disease Pathology
Aquarium fish can develop slime disease from several different protozoan parasites, such as Ichthyobodo necator, Ichthyobodo pyriformis, Chilodonella spp., or Trichodina spp.
If you believe your fish has slime disease, taking skin and mucus samples to analyze under a microscope will allow you to confirm the diagnosis. However, this process is difficult, and most hobbyists won’t be able to identify the parasite without help. If necessary, aquarium veterinarians can complete the work for you.
Although many aquarium fish enthusiasts still refer to slime disease infections as “costia” or “costiasis,” the correct terms would be ichthyobodosis, chilodonellosis, and trichomonosis, depending on the parasite present.
The Life Cycle of Slime Disease
The life cycles of aquarium fish slime disease parasites are different in some fundamental ways, but Ichthyobodo necator is broadly representative. Like other members of its species, Ichthyobodo necator has a free-living swimming stage and a parasitic feeding stage.
The free-living stage of this parasite involves swimming through the water with its two flagella until it stumbles upon a host. It will die if it does not find one within a few days.
Upon attaching to a host, the creature begins to feed on skin tissue–primarily dead skin cells, but also some live ones.
Most aquaria contain Ichthyobodo, Chilodonella, and Trichodina. While small numbers of these harmful parasites don’t generally affect fish, they can develop slime disease symptoms under aquarium conditions where fish are stressed or weakened.
How Can I Treat Slime Disease?
The slime disease treatment plan will depend on the specific aquarium fish slime parasite and aquarium conditions. However, there are some general steps you can take to combat aquarium slime disease:
- Feed your fish a well-balanced diet and keep them in optimal water conditions. For instance, aquarium fish tend to be more stressed when their aquariums are overcrowded or don’t have the proper pH balance.
- Consider a quarantine aquarium for new aquarium fish, especially if you plan on introducing them into a tank with existing fish.
- Test aquarium water regularly and make any necessary aquarium water changes to remove toxins that can weaken your fish.
- Verify that the aquarium equipment (e.g., filtration systems) is working correctly and performing its intended function.
- Consult aquarium vets or aquarium specialists for help identifying aquarium slime diseases in fish, especially if your aquarium fish are showing severe symptoms. With the correct identification, you can choose the most effective treatment option for your aquarium fish.
What Are the Best Medications To Treat Fish Slime Coat Disease?
Many commercial medications can help treat slime disease—one of them is fish Keflex. This aquarium fish medication, and others like it, provide the correct antibiotics to your fish to help them heal and fight off slime disease.
In addition, you can purchase commercial medications for slime disease that typically contain formalin. Other active ingredients used in these products include copper sulfate and potassium permanganate.
However, be sure to use the medication as directed on the packaging, paying attention to details such as dosages, durations, supplemental aeration, and removal of carbon from aquarium filters (if necessary).
How To Effectively Cure Slime Disease Using Salinity
The parasites that cause slime disease in aquarium fish are sensitive to salt, and slime disease can usually be treated through a combination of the following steps:
- Raising the water temperature to 86 degrees Fahrenheit (30 degrees Celsius)
- Adding salt at a dose of 0.4 to 0.7 ounces per gallon (3 to 5 grams per liter)
- Improving environmental conditions
- Maintaining warm, saline conditions for 7 to 14 days
However, not all aquarium fish can handle an equal amount of salt. Livebearers, killifish, cichlids, goldfish, and koi are pretty tolerant of salt, so the higher dosage is safe to use.
In contrast, soft water aquarium fish like tetras, barbs, rasboras, and gouramis aren’t as tolerant of higher salt levels, so it’s best to give them a lower dose.
Raise the salt concentration in your aquarium slowly over a day. This will give the fish and bacteria time to adjust to the new conditions.
Unfortunately, some slime disease parasites like Ichthyobodo necator are resistant to salt and cannot be killed using this method.
How To Treat Slime Disease With Saltwater Dips
While saltwater dips aren’t the only treatment you should give your fish for aquarium slime disease, they can help speed up recovery.
Adjust the salinity of the water to between 10 and 35 ppt (about one-third of full-strength seawater) for it to be effective. Then, dip them for 2-20 minutes.
To ensure your fish’s comfort, it is essential that you only use water that has the same temperature, pH, and hardness as their aquarium. Individual fish accustomed to swimming in saltier water will be able to handle this better than those from softer habitats.
In addition, keep a close eye on small fish as they stress more quickly than larger ones. You can tell if they’re experiencing severe stress if they start rolling over onto their side– at which point, remove them from the dip immediately.
While aquarium slime fish disease can be a serious and challenging condition to treat, there are many strategies you can use to address it effectively.
Whether you opt for commercial medications or saltwater dips, always take the time to properly care for your aquarium fish so that they have the best chance of recovering from this condition.
I hope this information is helpful. If you have any questions, please feel free to reach out to us at any time.
We wish you all the best in your aquarium journey!