American Underwater Services, Inc.


Commercial Diver & Dredging Services

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Why Are the Fish in My Pond Dying?

Finding one or two dead fish floating in your HOA or golf course pond isn’t a cause for concern. They could have met their fate due to a predatory bird, or perhaps they just got old and weak, and nature took its course.

However, when you start noticing a pattern of dead fish in your pond, it’s time to pay closer attention. The fish in your pond act as a natural barometer of health. They are very susceptible to changes in the water. Recurring fish kills could be an early indicator of something gone wrong.

Aside from old age, disease, and predatory animals, several other potential causes of a fish kill exist.

Water Pollutants

Most HOA ponds double as wastewater retention areas, making them susceptible to chemical runoff during rain events. Car oils, pesticides, herbicides, and any other manufactured chemical product found on the streets or in the garden can—and will—find their way into a stormwater retention pond.

If the chemicals don’t kill the fish outright, they can severely raise the levels of phosphates in the water, causing a nuisance algae outbreak and depleted oxygen levels.

Low to No Oxygen

Fish extract oxygen from the water to live. If your pond has low to no oxygen levels, the fish will tend to hover near the surface, moving their mouths as if they were gasping for air—and that’s precisely what they’re doing.

Lack of oxygen is the most common reason for fish kills in smaller ponds and lakes. Water warmed by the summer sun can quickly deplete the oxygen levels in your pond. If the fish population is too high, it can lead to a massive die-off. Algae blooms and invasive plant species produce nitrogen and phosphorus, which also contribute to oxygen depletion in the water.

If your pond doesn’t have a source of running water, a quick fix is to grab the garden hose and spray the water from side to side. The agitation will cause some oxygen to return to the water. You can also buy a mechanically powered aerator that will float in the pond’s center and serve as a more permanent fix.

Parasites and Diseases

Fish are highly susceptible to diseases and parasites. Even the slightest change in water chemistry, temperature, or pH can cause the fish to develop open sores, exhibit abnormal behavior, or become discolored.

While disease and parasites are part of nature, they can quickly spread out of control if the conditions in the pond are just right. Ponds are tiny and can’t “self-correct as quickly as larger bodies of water, leading to a chain reaction that can cause a massive fish die-off. One of the biggest causes of parasites and diseases is overfeeding and overstocking the water. Sometimes, well-meaning people will “dump their home aquarium fish into the pond when no one’s looking, and finding these kinds of abandoned fish is challenging, if not impossible. At this point, you might need to drain the body of water to remove the invasive species.

Preventing a Fish Die-Off

The above three examples are just a few of the many reasons fish are dying in your pond. One of the best ways to prevent a fish die-off is to ensure excellent water quality. At the very bottom of the pond is an area filled with organic muck. Bacteria can’t live at these depths, and the muck continually releases harmful nitrites and nitrates into the water column. This can cause algae blooms and lead to a chain reaction that will suffocate your fish from lack of oxygen. Dredging your ponds can remove this layer of rich organic muck and help prevent unsightly algae blooms as well as fish die-offs.

Nationwide HOA, Homeowner, and Golf Course Pond Dredging

At American Underwater Services, we specialize in HOA, golf courses, farms, and homeowner pond dredging. We can help you regain control over your ponds and turn them into crystal-clear water havens for fish, animals, and people alike. Call us today at (817) 377-8512 to learn more about our nationwide pond dredging and cleaning services. We can travel anywhere in the continental U.S. to help you with your dredging needs.




Anthony Di Iulio the founder, president and co-owner of American Underwater Services, Inc., started his business in 1999 with only three employees. Today this commercial diving company employs nearly 30 people and handles over 500 projects annually. Anthony moved to Fort Worth from Louisiana with his family in 1976. He worked summers during high school welding underwater for a marina on Benbrook Lake. Eventually he took scuba lessons after almost drowning on the job. Those lessons led him to training at a deep sea diving school in Houston, which included training on offshore oil rigs. Anthony spent several years in Louisiana working on offshore rigs and on inland jobs at power plants and dams before starting American Underwater Services, Inc.


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