Fish Kills in Ponds

Sarasota County provides help to neighborhoods in maintaining healthy stormwater ponds through the Neighborhood Environmental Stewardship Team (NEST). Occasionally, ponds may experience low oxygen levels that cannot support aquatic life, which can lead to fish kills. 

 Fish kills in ponds and lakes can be a common occurrence in Florida, especially during the summer.  In most cases, fish kills are the result of natural causes, but human activities, particularly nutrient pollution, can also cause or worsen these events. The most common causes of fish kills include:

• Warm water which holds less oxygen than cooler water. 
• Rainfall that has washed grass clippings and other vegetation into a pond where the decomposition process reduces oxygen levels.
• Fertilizer runoff that can fuel agal blooms and reduce oxygen levels. 
• Overcast skies that limit sunlight and reduce photosynthesis, the process by which aquatic plants produce oxygen.

In most cases, fish kills resolve on their own within a week or less. Fish are naturally removed by birds and other wildlife, as well as decomposition. Low-oxygen fish kills are natural occurrences and typically do not cause permanent damage to the ecosystem or to fish populations. Some species, like tilapia, are more likely to suffocate than other species.

Ponds that are less prone to fish kills tend to be more naturally balanced and less impacted by fertilizer and runoff. These ponds often have healthy submerged and shoreline vegetation, which helps maintain oxygen levels and overall water quality.
 

Report Fish Kills

To report a fish kill of concern call the Sarasota County Contact Center at 941-861-5000.
Fish kills may also be reported to the Florida Fish Kill Hotline at 1-800-636-0511 or online.
Learn more about fish kills at the Florida Fish and Wildlife Conservation Commission's Fish Kills webpage.