thumb|Murray cod ([[Maccullochella peelii peelii)]]
Percichthyidae, the temperate perches, are a family of freshwater ray-finned fish found in Australia and southern South America. Formerly placed in the order Perciformes, they are now placed in the order Centrarchiformes.
The name Percichthyidae derives from the Latin perca for perch and Ancient Greek ἰχθύς, ichthys for fish.
Evolution
Potential percichthyid fossil remains are known from the Early Paleocene of the El Molino Formation of Bolivia; these remains have been described as resembling those of the fossil Percichthys hondoensis from the Eocene of Argentina. One articulated specimen is known from the Paleocene portion of the formation, but other remains are known from the Maastrichtian beds of the formation, indicating that percichthyids could have potential Cretaceous origins. However, the condition of this material is unclear. Another fossil percichthyid, Percichthys lonquimayiensis from Chile, was initially dated to the Paleocene, but further studies have found it to be from the Miocene.
Potential percichthyid scales have been recovered from the Miocene-aged fossil deposits of Foulden Maar in New Zealand. If these are of percichthyids, this suggests they had a wider distribution during the Neogene. They also appear to have ranged as far north as the Neotropics during the Oligocene/Miocene, with the fossil genus Santosius known from Brazil.
Modern percichthyids have a significant disjunct distribution, being found in Australia and southern South America. All extant members of the group only inhabit freshwater habitats, and it is thus unlikely they ever evolved marine habits. For this reason, it is likely that the modern distribution of percichthyids derives from dispersal over the Antarctic land bridge between South America and Australia, which existed up to the end of the Eocene. This suggests that percichthyids likely inhabited Antarctica as well.
Almost 40 species of percichthyids are now recognised, grouped in 11–12 genera. Most but not all are exclusively freshwater fishes. They are mainly found in Australia, but species are also found in southern South America (Percichthys).
More recently the Chinese perches have been classified in the separate family Sinipercidae while the genus Percilia has been found not to be closely related to either that family or the Percichthyidae and has been placed in its own monotypic family Perciliidae. The two catadromous species in Percalates are found in Australia and were previously placed in Macquaria, but phylogenetic analyses have found them to be the most basal members of the whole order.
The following 8 genera are classified within the family Percichthyidae: