Updated September 16, 2014
When it comes to keeping your saltwater fish happy and healthy, there are a number of different diseases you must be on watch against. One of the most common, and most problematic, diseases affecting saltwater fish is parasites. There are a number of different parasites that might affect your saltwater fish, but a single treatment may be useful against a large number of them – freshwater. In this article you will learn the basics regardingcommon parasite infections to affect saltwater fish as well as tips for using freshwater as a treatment option.
Types of Saltwater Parasites
There are many different types of saltwater parasites with which your fish might come into contact, but some are more prevalent than others. The most common types of saltwater parasites include:
- Cryptocaryon irritans (Marine Ich)
- Amyloodinium (Velvet)
- Turbellarian (Black Ich)
- Brooklynella (Anemone Fish Disease)
Cryptocaryon irritans - Also known as Marine Ich, Cryptocaryon irritans is a fast-spreading parasite infection that results in myriad pinhead-sized gray nodules on the body, fins and gills of infected fish. This disease causes excessive skin irritation, respiratory distress, faded color and flashing.
Amyloodinium – Also known as Marine Velvet, Amyloodinium is one of the most deadly saltwater fish parasites. This disease can cause death in as little as 12 hours due to damage to the filaments of the gills. Early symptoms include increased respiration, sluggishness, gasping, and flashing.
Turbellarian – Also known as Black Ich, Turbellarian is caused by a flatworm. This disease causes dark spots on the skin which are actually a reaction to the parasite rather than a visible form of the parasite itself.
Brooklynella - Also known as Anemone Fish Disease, Brooklynella is a ciliated protozoa parasite that tends to infect the skin and gills of fish. This disease causes lethargy, respiratory distress, anorexia, discolored skin, and increased mucus production.
Using Freshwater Against Parasites
If you have ever owned a freshwater aquarium, the chances are good that you have used a saltwater bath to treat some type of freshwater fish disease. Just as you can use saltwater to treat freshwater diseases, you can also use freshwater to treat some saltwater diseases. The way this treatment method works is by exposing the parasites to a different salinity level than they are used to – this then causes a change in the osmotic gradient which draws water into the parasite’s body, causing expansion and bursting. It is important to note that freshwater is only effective against external parasites – it does not work for parasites that have burrowed into the skin or gills and for those that have entered the internal systems of the fish. Freshwater may not work as a treatment against all types of saltwater parasites, but it is certainly worth a try before you resort to harsh chemicals or medications.
Your first step in treating a fish with a parasite infection is to quarantine the fish. If you catch the infection early enough, you may be able to prevent the spread – if, however, multiple fish show signs of infection then you may need to dose the entire tank. Follow the steps below to use a freshwater bath as treatment for saltwater parasites:
- Quarantine the infected fish from other non-infected fishes in a hospital tank.
- Prepare a 5-gallon bucket of freshwater – make sure to match the water temperature, pH, and water hardness as closely as possible to the parameters in your main tank.
- Treat the water with dechlorinating solution to remove chlorine and other toxic chemicals.
- Use a mesh net to transfer the sick fish into the bucket.
- Let the fish rest in the freshwater bath for between 2 and 8 minutes, depending on the fish’s reaction to the treatment.
- Watch the fish carefully – if it starts to show signs of stress, return him to the quarantine tank immediately.
- Use the mesh net to transfer the fish back to the quarantine tank.
Tips for Preventing Parasites
While there are ways to treat parasite infections in saltwater fish, your best bet will always be to prevent them whenever possible. Parasites are opportunistic creatures so they are most likely to attack when your fish have already been weakened by injury, stress, or another disease. This being the case, the key to preventing parasites in saltwater fish is to keep your fish happy and your fish tank clean. Perform routine water changes on a weekly basis to keep water quality high and use a water test kit to monitor your parameters for changes which might cause your fish to become stressed. Offer your fish a healthy, varied diet of commercial, live, frozen, and freeze-dried foods to ensure that their dietary needs are met.
If you keep your saltwater aquarium clean, your fish are unlikely to be affected by parasites. You cannot possibly control every single factor, however, so it is possible that your fish might become sick no matter how careful you are. If your fish do succumb to a parasite infection, consider trying a freshwater bath before you resort to harsh medications or chemical treatments which have the potential to cause further stress and harm to your fish.