Tetrosomus gibbosus, commonly called camel cowfish because of the hump on its dorsal keel, is one of 22 species in the boxfish family, Ostraciidae.[2] It is a ray finned fish. Other common names include helmet cowfish, humpback turretfish and thornbacked boxfish. It is most closely related to T. reipublicae, the smallspine turretfish.[3]T. gibbosus is a species of boxfish found in the wide Indo-West Pacific. It has been recorded since 1988 on rare occasions in the Levantine waters of the Mediterranean Sea, likely following entry via the Suez Canal.[4] It is the first species from the family Ostraciidae to be found in the Mediterranean Sea.[5]
It carries some value in the aquarium trade, but is difficult to keep.[6]
T. gibbosus is normally around 20 centimetres (7.9 in) long when it is fully grown, but can reach up to 30 centimetres (12 in) in length.[7] Fish in the genus Tetrosomus are characterized by the presence of a carapace, a hard upper shell formed by thick scale plates.[3] The body is completely encased in this bony shell, except for a few small openings such as the mouth, eyes, and gills.[8] The mouth is small with fleshy lips and conical teeth usually numbering less than 15.[8]
T. gibbosus has poisonous flesh, organs, and spines, and is known to secret poisonous mucus in defense or when it is disturbed.[7] This poison can be fatal to humans or other marine organisms that come into contact with it.[7]T. gibbosus is hermaphroditic; all individuals of this species are born female, but some may change into males as they grow.[7] Juveniles live together in small schools, but individuals become solitary as they mature into adulthood.[7]T. gibbosus is an omnivorous species, and its diet is known to include seaweeds, sponges, molluscs, worms, and crustaceans found on the bottom of its habitat.[7]
T. gibbosus lives in shallow tropical waters or warm seas with muddy bottoms and can sometimes be seen near shallow seagrass beds.[9][8] It is also found in coral reefs.[10] It is considered an endangered species in the South China Sea.[10]
ALessepsian migration refers to the migration of a marine species from the Red Sea to the Mediterranean Sea, facilitated by the opening of the Suez Canal in 1869. A species is considered Lessepsian when it has completed this migration and established a population. T. gibbosus was first found in the Mediterranean Sea in 1988.[11] Both the Red Sea and the Mediterranean Sea have similar salinity levels and temperature ranges, which allows for an easier transition between of these bodies of water.[12][5] It is thought that Lessepsian species migrated due to changing climates, since the geographic land barrier was removed when the Suez Canal was completed.[11]T. gibbosus is now considered an invasive species in the Mediterranean Sea, as this is not included in its native distribution.[11] It is also considered an established species because it has established a growing population and has been found in multiple locations.[12] It is the first species from the family Ostraciidae to be found in the Mediterranean Sea.[5] Due to its inability to swim long distances, T. gibbosus likely took multiple generations to migrate from the Red Sea to the Mediterranean Sea; this is thought to have happened, in part, from northward currents moving eggs and larvae north towards the Mediterranean Sea.[5]
