2024-04-19 20:00:00
Eand fish of two and a half meters in length and 150 kilograms, which you will not simply find at the fish stall on the market. It is the arapaima, perhaps the largest freshwater fish on earth. Apparently specimens of almost four meters in length once lived there!
Rotterdammers may be familiar with the fish species, because until last week two of these whoppers were in Diergaarde Blijdorp. They have now moved to a more spacious home in the Duisburg Zoo. That move was a major logistical challenge, because how do you transport such a large fish? In a large container of water would be an obvious answer, but that is too simple.
The animals are so large that ‘normal’ breathing using gills is not sufficient. Their swim bladder has been transformed into a kind of lung and the arapaimas have to come to the surface at regular intervals to take a breath of air. This offers the great advantage that they can also live in murky and oxygen-poor water, such as lakes that are not connected to a river for a while during the dry season and therefore do not receive a fresh supply of oxygen-rich river water. But the fish lung also ensures that the fish can drown. The risk that sloshing water might enter the lungs was the biggest challenge during transport.
The fish were transported in water-filled hammocks placed perpendicular to the direction of travel of a heated truck to prevent sloshing. In the end it worked; The collaboration between the two zoos led to a record: never before have such large fish been transported alive over the highway.
An 18 meter long aquarium glass
The Rotterdam arapaima now swim in Duisburg in a huge tank together with three small specimens and some other animals. They can be viewed through an 60-foot aquarium glass. If you want to see how the transport went, you can visit the website of the German zoo where an informative video can be found.
Arapaimas belong to a family of fish called Osteoglossidae, literally bony tongues. This was once a species-rich group, but today only a few species remain: two in Australia, two in Asia, one in Africa and four or five in South America. All bony tongues live in tropical freshwater, but fossil forms have been found that also lived in the sea.
The colossal arapaima, which goes by the appropriate scientific name Arapaima gigas, is a formidable predatory fish. His menu mainly includes fish (including piranhas!), but also crustaceans and small mammals that venture to the water’s edge; fruits are also eaten.
They are somewhat strange fish, with a huge body and a relatively small head with a large mouth and small eyes. The fish body is covered with large round and rough scales that form a hard armor. The beak is not only used for eating but also to protect the young for a while following they have hatched.
Arapaima were and are fished for consumption and overfishing was therefore threatened; Thanks to conservation measures, things are now doing a little better.
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