7 Common Diseases & Health Issues in Freshwater Shrimp: How to Treat Them

Freshwater shrimp are relatively easy to care for but they do tend to be quite delicate. They’re sensitive to changes in water chemistry and require a fully cycled tank in order to thrive. Even with clean water and a healthy diet, however, freshwater shrimp can succumb to disease.

Understanding the basics about freshwater shrimp diseases is the key to early diagnosis and prompt treatment. Here’s what you need to know about the most common diseases and health issues in freshwater shrimp and how to treat them.

1. Scutariella Japonica

Perhaps the most common parasite known to affect freshwater shrimp is a type of flatworm or parasitic nematode called Scutariella japonica. These parasites typically inhabit the gills or mantle of infected shrimp. Though Scutariella japonica are unlikely to cause any serious harm in small numbers, if they’re allowed to reproduce unchecked, they can affect the affected shrimp’s ability to breathe, eat, and, ultimately, survive.

In the early stages of Scutariella japonica infection, you may notice small, white, stick-like growths on the top of the shrimp’s head. These growths will be about 1 to 2 millimeters long and may eventually spread to the gills. In some cases, the parasite will lay eggs in the shrimp’s gills or head.

Treatment: The safest method of treatment for Scutariella japonica in freshwater shrimp is aquarium salt. Dissolve about 1 tablespoon in a cup of tank water then add the infected shrimp to the cup for 30 to 60 seconds before returning it to the tank. Alternative treatments may include Seachem’s ParaGuard, and praziquantel, both of which can be used to treat the whole tank.

2. Holtodrilus Truncates

Similar to Scutariella japonica, Holtodrilus truncates are organisms that can be found living on freshwater shrimp. They’re small, worm-like creatures classed as obligate epibionts and they typically anchor themselves on the underside of the shrimp directly between the pleopods.

Holtodrilus truncates do not feed on their hosts, but their presence can be distressing for the shrimp. When freshwater shrimp become distressed, they may become weak or lose color. In some cases, the infestation may lead to gill damage which can be fatal for the shrimp.

Treatment: Holtodrilus truncates are notoriously difficult to eradicate because they spread very easily and are resistant to standard parasite treatments. The most effective treatment may be a simple salt bath, as described in the previous section.

3. Bacterial Infection

When it comes to freshwater shrimp diseases, bacterial infections are tricky. The signs are often difficult to spot at first, but they spread quickly and can become fatal. It’s easy to miss the infection entirely in opaque species but in transparent shrimp like Amano shrimp and ghost shrimp, you may be able to observe changes to the internal organs. They might swell or turn black.

Little is known about bacterial infection in freshwater shrimp. It’s difficult to diagnose and, once the signs become obvious, the shrimp may only live a few more days. Treatment is unlikely to have much effect at that point.

4. Chitinolytic Bacterial Disease

Also known as rust disease, chitinolytic bacterial disease differs from other bacterial infections because it affects the outer rather than the inner organs of the shrimp. The umbrella term “chitinolytic” covers many genera of bacteria including Pseudomonas, Flavobacterium, Benekea, Spirillum, Aeromonas, and Vibrio.

The most common signs of chitinolytic bacterial disease in freshwater shrimp are dark spot-like lesions that form on the exoskeleton which may progress to more widespread degradation. The bacteria responsible for chitinolytic bacterial disease possess an enzyme called chitinase which breaks down the shrimp’s carapace. Once the shrimp’s carapace is damaged, the disease may spread internally.

Treatment: Though rust disease may not be immediately fatal to infected shrimp, it is progressive and can be very dangerous. Treatment is possible only during the early stages and may not always be effective. Remove filter media from the tank then increase aeration and turn off the lights. Add 3% hydrogen peroxide at a rate of 1.5ml per gallon, spreading it evenly. After an hour, turn the light and filter back on then repeat three days in a row.

5. Fungal Infections

While fungal infections are more common in fish than in freshwater shrimp, they can be dangerous when they happen. As long as your shrimp have a strong immune system, they should be able to resist fungal infections. If their health is already compromised, however, or if they are stressed, they may be susceptible to a fungal infection known as mycosis which can damage the internal organs.

Internal fungal infections can be difficult to diagnose but some external infections are visible to the naked eye. Achlya and Saprolegnia infections, for example, may present as white residue forming on the outer shell which may progress into a cloud-like growth. In minor cases of external fungal infection, molting may remove the issue.

Treatment: The best treatment for fungal freshwater shrimp diseases is API Pimafix. Simply add 5ml per 10 gallons of tank water daily over seven days. After seven days, perform a 25% water change.

6. Ellobiopsidae

As is true for fungus in the aquarium, ellobiopsidae are likely already present in the tank and shouldn’t be a problem if your shrimp are healthy. Ellobiopsidae are, however, parasitic and can kill your shrimp if they get into the shrimp’s muscles, blood, or digestive tract.

Though very hard to treat, ellobiopsidae infestations are easy to spot. These parasites reproduce by sending out spores which you can see on the bodies of shrimp. It may appear as a cottony yellow or green growth on the shrimp’s outer membrane.

Treatment: The best treatment for ellobiopsidae is a malachite green product. Treating the tank with copper may be effective as well, but copper is extremely dangerous for shrimp, and it can be tricky to get the dosage right to kill the parasite but not your shrimp.

7. Muscular Necrosis

This is one of the more common freshwater shrimp diseases and it is easily identified by loss of color on the body of the shrimp. Infected shrimp also frequently display milky-colored spots on the lower ends of their bodies. Muscular necrosis is a disease in which the shrimp’s muscle cells die off and it may be caused by poor water quality, lack of nutrients, or weakness due to bacterial infection. Because the exact cause is unknown, there are no known treatments.

When it comes to keeping your freshwater shrimp healthy, the best thing you can do is maintain stable water chemistry. Perform weekly water changes and make sure you have adequate shrimp-safe filtration in your tank. Test your tank water weekly as well to stay on top of any issues.

It’s also wise to familiarize yourself with the signs of common freshwater shrimp diseases so you can identify them in the early stages when they might still be treatable.