"Biologists from FWRI's Age & Growth Lab estimated the age of this fish at 50 years old, making this the oldest sample collected for our ageing program," the FWC said. "Acquiring the otolith from this fish was extremely valuable as samples from larger and older fish are rare."

Otoliths are the hard structures located behind the brain of bony fishes, according to the FWC. They help fish hear, maintain balance and orient themselves. Scientists use the growth structure of otoliths to estimate a fish's age.

Warsaw groupers can grow to a length of 7.5 feet (2.29 metres) and weight of 580 pounds (263 kilograms). The record for the largest one caught in Florida is nearly 440 pounds (199.5 kilograms).

"Warsaw are characterized by an elongated second dorsal spine," the FWC said. "They're the only grouper with 10 dorsal spines; all others have 11. Although adults usually occur in depths of 180-1700 ft, juveniles are occasionally seen around jetties and shallow-water reefs in the northern Gulf."

The FWC said it "does not encourage the targeting of Warsaw grouper," as the species' population in the Gulf of Mexico isn't known.