how to treat whirling disease in fish

Why is Whirling Disease harmful?

Salmonid fish suffering from Whirling disease suffer from skeletal deformities and neurological damage. Fish that are infected find it difficult to eat or avoid predators because of their “whirling” motion. Salmonid fish have a high mortality rate, accounting for up to 90% of infected populations. Those that do make it through are deformed due to parasites living in their cartilage and bones.

The devastating effects of Whirling disease are being felt by North American coldwater fisheries.

Myxobolus cerebralis was initially found in Pennsylvania in 1956 after being brought to the country by infected trout that was imported from Europe. For many years, rainbow trout in hatcheries were thought to be susceptible to whirling disease, which could be controlled. However, the issue gained national attention in the 1990s when whirling disease was connected to serious effects on wild trout populations in Colorado and Montana. As a consequence of the disease, some streams in the western United States have lost 90% of their flow.

Whirling disease affects the health of popular sportfish, which has an impact on anglers. All salmonid species are susceptible to Whirling disease, although Rainbow and Cutthroat trout are the most commonly affected. Bull Trout, Brown, and Grayling may contract the parasite, but they don’t seem to be susceptible to it. Certain species may still transmit the disease even though they are not susceptible to whirling disease. Carriers with no visible signs of disease are common.

Harmful Aquatic Hitchhikers: Others: Whirling Disease

Salmonid fish, which include trout, salmon, and whitefish, are susceptible to whipping disease. Myxobolus cerebralis, an invasive parasite, is the cause of the illness. The parasite enters salmonid fish through the cartilage in their heads and spines, where it multiplies quickly and puts pressure on the organ of equilibrium. Because of this, the fish swim erratically, making it difficult for them to eat and avoid predators. The disease can also manifest physically as a darkened tail, twisted spine, or malformed head. In severe infections, whirling disease can cause death.

For fish infected with the whirling disease parasite, there is no known treatment.

The life cycle of the whirling disease parasite alternates between a small worm and a fish. The parasite cannot finish its life cycle without these two hosts, and it will perish without proliferating. The worm host of the parasite is called Tubifex tubifex. This tiny worm, which is about half an inch long, is widely distributed and common all over the world. The fish host is a salmonid fish.

A muddy river bottom can contain up to 10,000 Tubifex tubifex worms in one square yard.

During its life cycle, the parasite takes several physical forms. Among these are two infectious spore forms known as triactinomyxon (TAM) and myxospore. The tubifex worm is infected by a tiny, round spore called a myxospore. The myxospore inside the worm transforms into a TAM. The TAM is then discharged from the worm into the water column, where it floats until it makes contact with a fish that is vulnerable. The parasite is injected into the fish’s body by the TAM, which clings to its skin. Once within the fish, the parasite proceeds to the head via the neural system, where it feeds on cartilage and starts to grow. The parasite transforms inside the fish to revert to a myxospore. When an infected fish dies and starts to decompose, the spores are released into the environment or can be shed from the gills or feces. Many thousands or even millions of disease-causing spores can infect a single fish. Myxospores that have been released return to the soil to continue the infection cycle.

Myxospores in the sediment can live for over 20 years.

Myxobolus cerebralis is a native of Europe that was initially found in Pennsylvania, USA, in 1956. Since then, reports of it have come from multiple states, and it is still spreading. The severity of the effect varies amongst water bodies, so the presence of the parasite does not always indicate a sharp decline in fish populations. Because the parasite does not infect humans or predators that consume infected fish, eating salmon and trout that have whirling disease is safe.

Research on the effects of the whirling disease parasite on wild trout populations and strategies for mitigating its spread is still being conducted by the DWR’s Aquatic Animal Health and Research Center. As part of this endeavor, new waters are surveyed every year to ascertain the total amount of the whirling disease parasite in the state.

According to scientists, there may be additional negative consequences, such as making fish less able to feed, reproduce, or withstand environmental disturbances or more vulnerable to predators. Long-term whirling disease impact studies have recently been started by fisheries researchers, but no firm conclusions have been reached. However, experts have reevaluated the impact of parasites due to population collapses in well-known rainbow trout rivers like the Colorado and Madison.

The most vulnerable species in Utah are rainbow trout, which are followed in importance by kokanee salmon, golden, cutthroat, brook, brown trout, and splake. Recent discoveries show whitefish may be infected as well. Under laboratory conditions, lake trout can become infected, while other game fish species like walleye, bass, bluegill, and perch are immune to whirling disease.

The DWR found whirling disease in Utah in 1991 in a number of private hatcheries and nearby waters in Wayne County’s Fremont River drainage. At first, the parasite was thought to be eliminated by keeping fish out of those streams and reservoirs for an extended amount of time. Following the failure of that attempt, the parasite has been discovered in a number of commercial hatcheries, one state hatchery, and waters in the counties of Cache, Weber, Beaver, San Juan, Summit, and Sevier.

DO wipe off any debris from all fishing gear, including boats, trailers, boots, waders, and float tubes, before departing the area. Thoroughly dry equipment in the sun if possible before reuse. Use a different set of equipment or clean yours with a 10% chlorine bleach solution if you are going directly to other bodies of water.

FAQ

How do you treat aquarium fish whirling?

There is no known cure for fish infected with the whirling disease parasite. The whirling disease parasite has a two-host life cycle, alternating between a small worm and a fish. Without these two hosts, the parasite cannot complete its life cycle and will die without multiplying.

Can fish survive whirling disease?

Young rainbow trout populations infested with whirling disease may experience mortality rates as high as 90%. The parasite itself doesn’t directly kill its host, but infested fish are more susceptible to predation, have difficulty eating and are less likely to survive distributions in their environment.

What kills whirling disease?

✓ There is no known cure or vaccine for whirling disease.

Is whirling disease treatable?

Whirling disease is an infectious disease of finfish. It is caused by a parasite called Myxobolus cerebralis, which belongs to a group of microscopic parasites in the Class Myxosporea. There is no treatment for whirling disease.