Common Pond Fish Illnesses & How To Remedy Them

As gardeners, we are always very aware of health problems with our plants, as they are easy to spot and diagnose. However, pond problems more often can go undetected. Here are a few solutions to the most common problems that may appear.

Finrot
If your fish have Finrot, their fin edges are white and the fins become ragged and streaked with blood, appearing "eaten away," which is exactly what the bacteria that cause this disease are doing. Finrot is a classic sign that your pond has an environmental problem, so it is essential to check water quality for raised levels of ammonia and nitrite, and/or low pH.

Test your pond water for pH, nitrates, nitrites, alkalinity, and ammonia by using a Pond Test Kit. When poor water quality is detected, a large (30-50%) partial water change should be undertaken and any excess debris removed. To raise alkalinity or KH, use a calcium carbonate product, such as TetraPond WaterBalance. If using a municipal or treated water supply, be sure to use a water conditioner like TetraPond AquaSafe® to remove harmful chloramines. Also, be sure to keep your filtration system operating at peak efficiency with regular cleaning.

Skin Ailments
If fish are rubbing against underwater objects and jumping, it can be an indication their skin is irritated by parasites. In severe cases, they swim in a listless fashion with fins folded against their body and often isolated from other fish. Closer inspection may reveal a slimy coating over the body or in patches—particularly obvious against dark areas of the body and eyes. The irritation may be caused by poor water quality, skin and gill parasites (e.g., protozoans––costia, chilodonella, whitespot), and flukes. To treat, if all fish are affected, check the water quality using a test kit. Treat the parasites in the pond with TetraPond Pond Fish Treatment.

Fungus appears as tufts of white, like a "cotton wool" material, usually in patches on the fish's body. This secondary bacterial infection is a sign of damage. Again, the remedy is straightforward using a broad-spectrum treatment such as TetraPond Pond Fish Treatment.

Ick or Whitespot is just that––small white spots on the fins and body of your fish. Due to its complex lifecycle, this parasite must be killed with seven-day treatments. On day one, treat your pond with a broad-spectrum remedy such as TetraPond Pond Fish Treatment. Seven days later, repeat after a 20% water change. Repeat treatment at seven daily intervals if necessary.

A Salt Dip Can Benefit Your Sick Fish

Sick fish should be removed from the pond to a treatment container (e.g., an old wading pool or aquarium), whenever possible, to prevent disease spreading to the other fish. Make an un-iodized salt dip by using Pond Salt (available at your local pond retailer). Dissolve 2.5 cupfuls of Pond Salt in 10 U.S. gallons of pond water making a 2.0% solution. Gently place fish in a soft nylon net, then lower them into the salt dip for 5 to 10 minutes, no longer. As a result, a majority of microscopic parasites that kill fish will drop off the fish. Salt dips are the least toxic method and quite effective.

After You've Diagnosed Your Problem

If more than two or three fish are affected, or if the disease is infectious, it is necessary to treat the pond. Before doing so, change 10% of the water and remove excess debris. To ensure the disease remedy is evenly distributed, the required dose should be mixed with a little pond water and spread over the pond surface using a clean bucket or watering can.

"Sudden" losses of fish are often attributable to low oxygen levels in the water, particularly in well-planted ponds since oxygen levels decline at night when plants and fish compete for limited oxygen in the warm water. Extreme hot weather will also decrease oxygen. Ensure maximum water aeration by keeping waterfalls and fountains running at night as well as in the daytime.

For more information, you can also check out Tetra’s “Fish Illnesses – How to Spot Them” page, as pond fish can be afflicted with many of the same problems.
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