What are those large, silver fish in our Shipwreck aquarium? As I’m sure our volunteers can attest, we get this question several times a day. The answer, of course, is tarpon, Megalops atlanticus. Interestingly, not only are tarpon the largest fish we have, but they are one of the most unique!
Tarpon have many different adaptations that allow them to thrive throughout Florida and the entire Atlantic Ocean. For example, tarpon can breathe air! Like most fish, they have a swim bladder that helps them stay neutrally buoyant in the water; in other words, so that they do not sink or float.
Unlike other fish, a tarpon’s swim bladder has an opening to their mouth, and they can gulp air at the surface and move it into the swim bladder. Their modified swim bladder looks like a lung, with a lot of surface area for gas exchange, allowing them to take in oxygen to breathe. This adaptation allows them to hunt in low-oxygen waters like canals and rivers. Yes, I did say rivers, as in freshwater. Tarpon can live in any water body regardless of how much salt is in it, from completely freshwater to full strength saltwater.
In addition, tarpon have an upturned mouth allowing them to consume fish at or near the surface, like mullet, a favorite meal. They feed, as many fish do, by suction. Suction is created by opening their mouth very quickly which will pull fish deep into their throat where they swallow it whole.
Also, tarpon have the largest scales. You can clearly see them on the sides of the fish, and that is only 20-30% of the whole scale showing. Large tarpon have scales that can be the size of a person’s hand! Speaking of large tarpon, they can get up to a maximum length of eight feet and weigh over 300 pounds! More commonly, they are approximately six feet in length and weigh around 150-200 pounds. And they start their life as a less than a one-inch clear ribbon-like leptocephalus larvae. Over the next month or more, they grow to be about three to four-inch larvae and move from the open ocean where they are spawned to the mangrove and seagrass habitats where they transition to a juvenile that looks very much like a miniature version of the adults.
Finally, tarpon can live up to 50 years; there is one individual recorded in an aquarium to be 67 years old. We estimate that our larger tarpon are approximately 8-10 years old. And although they have many years to live, they will be a little too big for us to keep much longer. We are working with another aquarium to donate them to a larger facility where they can live out their days.