Living at depths that exceed 400 meters, the sunfish or springfish is considered the heaviest bony fish in the world. Appearing dispersed in various regions of the world, many individuals of this group are impressive due to their significant marks, such as the specimen found in Portugal in December 2021, weighing 2,744 kg and 3.25 meters in length.
Bony fish are those that have a skeleton formed predominantly by bones, unlike cartilaginous fish, which are formed by cartilage, such as sharks and rays.
Biologist and master in ecology and biomonitoring, Clarêncio Baracho explained to the UOL that sunfish are divided into five species and can be found in all temperate and tropical oceans around the world. Even on the Brazilian coast, where they can be observed near the Cabo Frio region (RJ).
“It is a fish that, although it can dive to deep regions, is often found close to the surface, but always in the oceanic region. However, in the productive region of Cabo Frio, characterized by the upwelling phenomenon, which brings cold and productive waters from the bottom to the surface, these animals are more easily found near the coast,” he said.
“They are clumsy swimmers, fanning their large dorsal and anal fins to move,” commented biologist Cadidja Gomes, who holds a bachelor’s degree in marine and freshwater biology from the University of Kingston in England. “Their food of choice is jellyfish, although they also eat small fish and large amounts of zooplankton and algae. They are harmless to people, but they can be very curious and often approach divers,” she says.
According to the biologist, it is common to observe it when the water temperature fluctuates between 13°C and 17°C. They are deep water fish and can develop in a range that goes from 30 to 480 meters deep. However, it is most commonly found between 30 and 70 meters. Despite marine currents, it is able to move both horizontally and vertically, thanks to the use of its fins.
It is estimated that the sunfish can live about ten years, being considered the most fertile vertebrate on the planet, as a single female can produce 300 million eggs. Hatched sunfish initially weigh less than a gram. One of the particular aspects of this species is its incredible size difference from when it is born until it becomes an adult.
Despite the high reproductive rates, in Brazil it is on the list of endangered fish and, in the world, it is in the vulnerable category of the IUCN (International Union for Conservation of Nature), an international entity that establishes the categories of threat to fauna. and flora of the planet.
“The sunfish are often caught in fishing nets, including those that are drifting, known as ghost nets”, explains Baracho. “They can also suffocate by ingesting marine litter, such as plastic bags, which resemble jellyfish, their main food.”
According to Cadidja, the researchers suggest the idea that this species makes migratory movements to latitudes where there is a greater concentration of zooplankton, mainly during spring and summer.
It is also suspected that it makes movements towards the surface to capture the animals that mainly develop in this area, such as some jellyfish and the smaller species on which they feed.
But this movement towards shallower areas is also not ruled out due to the infestation of parasites on their skin. “Often the infestation is so severe that they invite small fish or even birds, such as seagulls, to feed on the irritating creatures. They even jump out of the water in an attempt to get rid of these parasites”, says the biologist. .
In December of last year, a specimen of a giant sunfish was found by Rich German and Matt Wheaton, who were rowing in Laguna Beach, California. “It was two to three meters long, much bigger than I was,” German told the British tabloid Daily Star.
In March of the same year, a sunfish of the species masturus lanceolatus was found by surfers and caught the attention of those who passed by the Leste-Oeste beach, in Fortaleza. He appeared after the tide went out and ended up dying on the beach.