A fishing day in the D.D.

The Double Delta (D.D.) is the most biodiverse freshwater ecosystem of entire Antarctica. Reeds, brackish lakes, peatlands, riparian forests...any type of temperate wetland habitat can be found here. Fish diversity is very consistent, with over 100 species described. Most of them, are just marine fish clades that slowly adapted to less saline habitats, like Goldsardinas (Fluvisarniops aurum), distant relatives of sardines, that are the base of the trophic chain of the D.D. They are catadromous, like eels, living most of their life in freshwater and then moving to estuarine habitats for reproduction. Another once marine species is the long perch (Archaeoperca lungissima) that, despite its name, it's not a perch (Percidae) but a notothen (Nototheniidae), a fish family endemic to the Antarctic sea. It's relatively large and not very fast, eating mostly sessile organisms that live on the bottom of the lake and slow rivers. Despite being large, the long perch is nothing compared to the Primo (Primo salmonimorphus), the largest freshwater fish of Antarctica, that can sometimes exceed 2.5 meters (8.2 lbs), derived from a saltwater salmonid with semi-anadromous habits. It's the top predator of antarctic internal waters, capable of eating anything that fits in its mouth, even semi-aquatic birds such as ducks, tokas and icekissers.