Authorities are investigating what killed over 4,000 fish at a popular Bedford lake.
On July 26, Bedford city leaders responded to Boys Ranch Lake to investigate reports of a “substantial” loss of fish in the area, including catfish, sunfish and largemouth bass, according to a news release.
The cause is unknown. Bedford officials expect to share test results from samples taken at the lake later this week, said Molly Fox, the city’s director of communications.
The Texas Parks and Wildlife Department as well as Bedford Parks and Recreation collected samples and continued to remove the dead fish from the lake through Monday morning.
Catch-and-release fishing is allowed at the small community lake, which sits adjacent to Generations Park at the Bedford Boys Ranch recreation center. While the park remains open to the public, boats and swimming in the lake are not permitted.
The Bedford lake had a similar incident in July 2018. About 200 fish were killed that year after a break in a nearby water main released chlorinated water into the area.
At the time, residents expressed concern about the quality of the lake water and its impact on wildlife. The lake previously saw a massive loss of ducks in 2015 due to a virus, according to a report from NBC 5.
Large number fish kills, or “mass fishkills,” tend to increase in the summer, said Todd Sink, a Texas A&M aquaculture extension specialist and associate professor.
The Texas A&M AgriLife Extension Service, which responds to agricultural and wildlife issues across the state, receives an average of four to five reports of dead fish a week between May and September.
Most fish kills are seen in smaller, urban ponds, said Kirk McDonnell, Texas Parks and Wildlife Department spokesperson.
When investigating mass wildlife kills, biologists first examine dissolved oxygen levels, Sink said. Essential to aquatic life, oxygen levels can plummet due to high temperatures, decaying aquatic plants or harmful fertilizers.
Low dissolved oxygen levels is the leading cause of fish kills in Texas, Sink said.
“There’s 1.3 million (privately owned) ponds in the state of Texas,” he said. “There’s always something dying somewhere.”
Overpopulation of fish can also lead to lower oxygen production in water.
Toxins are another factor biologists look for, Sink said. Some plants produce bacteria that can become toxic to gill-breathing organisms, for example.
Low water levels and algae blooms are among the natural causes that lead to fish dying, McDonnell said.
Cities or local agencies frequently turn to aquatic equipment and technology to prevent fish kills, but they are still prone to occur, he added. Most are part of the environment’s natural process of adjusting fish populations to be sustainable in a habitat limited in resources, Sink explained.
“(Fish kills) are more widespread than anyone realizes,” he said. “It’s not always a dire, critical, scary thing.”
The Trinity River has seen its share of mass fish kills in recent years, two due to chemical leakage.
In 2022, a warehouse fire in the Foundry District led to low dissolved oxygen levels, causing a fish kill in the Trinity River, according to a Texas Parks and Wildlife Department investigation. The following year a water main break in downtown Fort Worth spewed high concentrations of chlorinated tap water, which flowed into the river.
Nicole Lopez is the environment reporter for the Fort Worth Report. Contact her at nicole.lopez@fortworthreport.org.
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Editor’s note: This story was updated July 30, 2025, with the estimated number of fish killed.
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