Abnormal Fish Behavior Event 2023-present
About the Event
The Florida Fish and Wildlife Conservation Commission (FWC) continues to document and investigate the cause of abnormal fish behavior (spinning) and small-scale fish mortalities in the Florida Keys that were first reported in fall of 2023. The critically endangered smalltooth sawfish are among the species that have been seen spinning, and while fish have not generally been dying in large numbers, sawfish mortalities have been documented at unprecedented levels.
The cause of the spinning fish behavior and sawfish deaths in the Florida Keys is still unclear. FWC and its partners are investigating various potential causes, but the best evidence so far points to harmful algal blooms (HABs) and their toxins. In late 2024-2025, we have the added complexity of a red tide bloom that impacted the Lower Keys. The spinning behavior is consistent with effects on the central nervous system such as could be caused by exposure to neurotoxins produced by some HAB species. Several HAB species capable of producing neurotoxins were found in water samples and toxins have been detected in fish tissue samples. Presence does not prove cause, and more research is needed to determine if these algae and toxins are responsible.
Reports of this abnormal behavior peaked in winter and spring of 2024 and then decreased during the summer of 2024. Although numbers in 2025 have been much lower overall, FWC continues to document cases submitted through the Fish Kill Hotline and the Sawfish Hotline.
The FWC continues to work collaboratively with universities, environmental groups, and government agencies at all levels to investigate and respond to the spinning fish event.
FAQs
Over 80 species impacted including
Angelfish, Atlantic Blue Tang, Atlantic Stingray, Ballyhoo, Barracuda, Bermuda Sea Chub, Bigeye Scad, Blacktip Shark, Blue Runner, Bluestriped Grunt, Bonefish, Bonnethead Shark, Boxfish, Bull Shark, Caribbean Sharpnose Puffer, Channel Catfish, Cowfish, Cubera Snapper, Dog Snapper, Eagle Ray, Filefish, Flying Fish, French Grunt, Glass Minnow, Goggle Eyes, Goliath Grouper, Gray Snapper, Gray Triggerfish, Grunt, Jack Crevalle, Lane Snapper, Leatherjacket, Lemon Shark, Lionfish, Long-Horned Cowfish, Lookdown, Mojarra, Mutton Snapper, Needlefish, Nurse Shark, Orange Filefish, Parrotfish, Permit, Pilchard, Pinfish, Pipefish, Porgy, Porkfish, Rainbow Parrotfish, Red Drum, Remora, Sailfish, Sand Perch, Sargent Major, Scaled Sardine, Scrawled Cowfish, Sheepshead, Silversides, Skate, Smalltooth Sawfish, Snook, Southern Stingray, Spadefish, Spanish Mackerel, Stoplight parrotfish, Striped Mojarra, Striped Mullet, Tarpon, Threadfin Herring, Tiger Shark, Toadfish, Tripple Tail, Trunkfish, White Grunt, White Mullet, Yellow Jack, Yellowfin Mojarra, Yellowtail Snapper.
Blue Crab, Florida Lobster, Horseshoe Crab, Spider Crab, and Stone Crab were also reportedly affected. However, only Horseshoe Crab and Spider Crab were observed exhibiting abnormal behavior.
All fisheries in the Florida Keys that are open, remain open. Please be sure to follow all rules and regulations when you head out on the water.
Harvesting distressed or dead animals is not advised under any circumstances. For more advice on consumption or to report a suspected fish-related illness, please contact your local county health department https://www.floridahealth.gov/index.html or call the Florida Poison Information Hotline 1-800-222-1222.
Swimming where there are dead fish is not recommended. Please report any fish kills to the Fish Kill Hotline, 800-636-0511 or MyFWC.com/ReportFishKill.