sick betta fish with gill fluke parasites

Gill Flukes: Betta Fish Parasites

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Having to deal with aquarium parasites is one of the last things you want to have to do, but usually happens to every hobbyist at least once. There are a few different types of common parasites that you will need to keep an eye out for, and it’s important to know how to treat them as soon as possible. One of these parasites is the gill fluke.

Keep reading to find out more about common aquarium parasites, gill flukes, and how to treat them in your own aquarium!

Betta fish parasites

Like other tropical fish, betta fish can succumb to aquatic parasites. While there are no benefits to having parasites in your system, betta fish can sometimes be easier to treat as they are usually the only fish in the tank, which eradicates the chance of the system being completely contaminated and losing all of your fish.

Two of the most common aquarium parasites are ich/white spot disease (Ichthyophthirius multifiliis) and gill flukes (Dactylogyrus sp.).

What does ich look like on a fish?

In general, ich is almost immediately identified as little white spots on the skin and fins of your betta fish, covering nearly every external surface. However, little white spots may also be a sign of velvet (mainly Oodinium sp. in freshwater fish), though those of velvet are usually even smaller and closer together and may not even be clearly visible.

Unfortunately, by the time white spots appear on your new fish, the parasite has already fully established itself in the aquarium and treatment needs to start right away. Early signs of ich might include lethargy, loss of appetite, and labored breathing; skin irritation may cause your fish to scratch against various aquarium decorations and the substrate. These stresses can subsequently lead to further injuries and overall weakness which can cause infection.

For more information about the ich life cycle and how to treat ich in your aquarium, make sure to check out our betta fish ich disease – symptoms, treatment, and prevention guide here.

What do gill flukes look like on a fish?

betta fish with gill flukes

Gill flukes are a little more difficult to identify than ich or velvet as these parasites are not usually visible on the skin to the naked eye. Without taking a skin sample and observing it under a microscope, you will need to make an educated guess as to if your betta has gill flukes or not; most of the time, you will not definitively know if your fish was truly suffering from gill flukes or another disease or infection.

Instead, gill fluke symptoms include your betta fish trying to gulp in the air at the surface, skin sores or discoloration around the gills, clamped fins, mucus around the body and gills, and scraping against various objects. Like ich, this can lead to secondary infections which can make recovery more difficult.

Gill flukes

But what are gill flukes? And why are they so deadly to your betta fish?

Gill flukes are part of the Dactylogyrus genus and are considered monogeneans; monogeneans are a type of parasitic flatworm that does not require an intermediate host. Because they can be livebearers or egg producers and they don’t need an intermediate host in between larval and adult stages, gill flukes can quickly reproduce and find hosts without needing another organism.

Adult gill flukes are hermaphroditic, meaning they have both female and male reproductive organs. These adults either give birth to live larvae or eggs; it is believed that adult gill flukes can produce 4-10 eggs every day. Once these eggs hatch, they have less than 8 hours to find a viable host; this free-swimming water movement is facilitated by cilia. The time between larva and adult is water temperature-dependent, with cooler water temperatures slowing down maturation rates dramatically.

How to treat gill flukes

Since you may never be entirely sure that what you’re facing are gill flukes, correct and successful treatment methods can be a little difficult to find. It is best to first remove your betta from the main display and place them into a more controllable quarantine tank; this tank should match in water parameters, have a heater, and have plenty of surface agitation for plenty of oxygen for your betta. However, keep in mind that your entire display tank is now full of gill flukes and will need to be treated as well.

Once your betta has been transferred, you will need to start dosing medication. For gill flukes, hobbyists recommend PraziPro. Dose as instructed. Salt dips may also help speed along with recovery, though are not recommended if you are not prepared/experienced as this may stress out your betta even more. Another popular method is using flubendazole instead of PraziPro; again, dose as instructed and supplement salt dips if confident.

It is important to keep in mind that gill fluke eggs and larvae are still living in the substrate and water column of the display tank. Larvae can only live 6-8 hours without a host and then they will die, but it is believed that adults can live up to one week without a host. However, in order to make sure that all traces of gill flukes are gone from the tank, it is recommended to perform regular large water changes, replace filter media, and vacuum the substrate regularly. Your betta fish will most likely need a couple of weeks to completely recover in quarantine, so the tank should be ready after about 14 days.

If your betta fish needs longer than this, you may need to keep an eye on the water parameters in your tank. Since nitrifying bacteria isn’t being fed by fish waste, the lack of nutrients could cause a mini water cycle. In this case, it might be necessary to manually introduce ammonia into the water column to sustain the beneficial bacteria.

Note: PraziPro and flubendazole cannot be prescribed for ich or other infections, so if you do not see an improvement, white spots start to develop across your fish, or your fish develops skin sores, be prepared with medications for ich, velvet, as well as other immunity boosters.

How to prevent gill flukes

Because gill flukes are invisible to the naked eye, it can be hard to tell if a potential new betta fish has been affected. It is best to observe the other fish within the tank, as well as throughout the whole store. Check for other symptoms, like lethargy, open sores, and rubbing against decorations; if the fish is particularly expensive or rare, it would be worthwhile to ask to see feeding.

Once a healthy betta fish has been selected, quarantine the new fish in a separate tank for up to a month. This should be enough time to monitor and treat any outbreaks of infection or parasites. If your betta gets gill flukes in an already established tank, you will probably have to set up a quarantine tank regardless, so it is better to be prepared and take your time!

Lastly, keep the water quality of your tank good at all times. Poor water quality can compromise the immunity of your betta fish and leave it even more susceptible to diseases, infections, and parasites. Even if your betta ends up with gill flukes, good water quality is a must if you want to give your fish the best chance possible of recovering.


betta fish with gill flukes in black background

Having any type of disease, infection, or parasite in your fish tank is not a fun time. It can be a stressful couple of weeks trying to get your betta fish to recover from gill flukes, but it is possible! The key is to look for early warning signs of lethargy, loss of appetite, discoloration around the gills, and scratching against decoration. Make sure to remove your betta fish from the tank as soon as possible and begin treatment for gill flukes if there are no other signs of ich, velvet, or another aquarium parasite.

If you have any questions about gill flukes, gill flukes on fish, or have had experience eliminating these nasty parasites from your tank, don’t hesitate to leave a comment below!

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