Bonefish & Tarpon Trust
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Spinning Fish in the Florida Keys

florida sawfish

Bonefish & Tarpon Trust (BTT) and the Lower Keys Guides Association (LKGA) received the first report of fish in the Florida Keys exhibiting abnormal, spinning behavior in early October 2023. Fish with the “spins” experience loss of equilibrium, causing them to swim upside down in repeated circles, often following a stressful or stimulating event.

Sawfish MortalitiesFWC Fish Kill Hotline ReportsLKGA Symptomatic Fish ReportsSymptomatic Species Reported
32404Over 180Over 50

*Table updated April 5, 2024

Over 50 species have exhibited these abnormal behaviors, including silver mullet, tarpon, permit, snook, bonefish, pinfish, bigeye scad, ballyhoo, jack crevalle, yellow jack, blue runner, southern stingray, mutton snapper, mangrove snapper, cubera snapper, lane snapper, leatherjacket, yellowfin mojarra, scaled sardine, toadfish, goliath grouper, blue striped grunt, redfish, lemon shark, Atlantic sharpnose shark, smalltooth sawfish, and spadefish.

An inter-institutional research study to identify the cause of these symptoms began on January 11, 2024. Partners include Bonefish & Tarpon Trust, Lower Keys Guides Association, Florida Gulf Coast University (FGCU), University of South Alabama (USA),  Florida International University, Woods Hole Oceanographic Institute (WHOI), Florida Department of Environmental Protection (FL DEP), and Florida Fish and Wildlife Conservation Commission (FWC).

Symptomatic fish continue to be observed consistently and are more frequently observed at night.  As of mid-March 2024, BTT and the Lower Keys Guides Association have received 182 reports of symptomatic fish, with almost all reports from inshore seagrass and flats systems. This stressor has affected forage fish, game fish, sharks and rays—and everything in between. Only two reports have been from the reef, Hawks Channel or shallow and deep gulf waters. The remainder have occurred in our inshore seagrass and flats systems. In mid-February, most of the reports occurred west of Big Pine Key and east of Sugarloaf Key, but have now expanded to the east and west.

Helpful Links

Initial Research Findings

In the collaborative study led by BTT and LKGA, four lines of inquiry are being explored. These include: contaminants and synthetic compounds (FL DEP, FIU), water column harmful algal blooms (FWC), benthic harmful algal blooms (FGCU, WHOI, USA), and fish health (FWC). BTT and LKGA have coordinated and executed multiple sampling events to collect symptomatic fish and paired water samples.

Initial results have found that:

  • All sampled fish showed no virus or parasites, or any organ abnormalities.
  • No red tide was detected in surface water samples, and FL DEP did not detect common contaminants.
  • Benthic harmful algal bloom samples identified elevated concentrations of a dinoflagellate in the genus of Gambierdiscus occurring in areas where symptomatic fish are present. Gambierdiscus can produce multiple types of toxins that can have adverse impacts to fish and potentially people.

Ongoing toxin testing will determine its overall impact and potential impact to fisheries. As we learn more, we will provide information on BTT’s social media channels and update this page.

Watch the March 2024 Live Update


How long will it last?

We do not know. As we are still trying to determine the cause, we do not know how long it will last.

Is it safe to eat fish?

Always consult with Florida Department of Health Fish Consumption Advisories:


There are always small risks of eating wild caught animals, whether that’s a deer, ducks, or fish and shellfish. Like with any wild animals, if individuals look sick or are with others showing symptoms, it is best to avoid eating them. If fish are exhibiting erratic behavior or fish are in areas where other fish are exhibiting such behavior, avoid eating them. Use your best judgment, it is better to be safe than sorry.

Is it safe to swim in the water?

Always consult with Florida Department of Health Swimming Advisories:


There are always small risks associated with swimming in the ocean. It is not advisable to swim in the same waters with many dead fish.

Will this spread?

We are still trying to determine the cause, therefore it is not possible to know if it will spread beyond the Florida Keys. 

If a fish is spinning, is it going to die?

Ongoing studies are evaluating this. These lines of work suggest that recovery is possible for some species.

What can we do?

Report erratic fish behavior to the FWC fish kill hotline or using this form from the Lower Keys Guides Association. It is essential that these reports reach the scientists. If you see a stressed sawfish, please report it to the sawfish hotline (844-472-9347).

Is this related to Wastewater Treatment Plant effluents?

Ongoing efforts by Florida Department of Environmental Protection and Florida International University are testing water for over 35 different human contaminants such as pesticides, pharmaceuticals, and heavy metals. So far, all common human contaminants have been measured at either background levels for the Florida Keys, or were not detected at all.

Could the dispersants or crude oil from the BP Oil Spill have caused this?

A wealth of data has been collected over the past 14 years since the Deepwater Horizon spill and while sublethal and acute exposure to crude oil can have negative impacts on marine organisms, they are not consistent with what we are seeing in the current event in the Florida Keys.

Support BTT Research

Along with LKGA, BTT has been on the front lines of this emerging concern from the beginning. Together, we’re making progress, but there is still much more to do. Please join the fight today and help us continue this important work! Your financial support will help BTT determine the drivers of this event, monitor its potential spread, engage with local fishing guides and partners, and produce science-based recommendations to mitigate future impacts.

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