The estuary perch, Macquaria colonorum, is an Australian species of the Percichthyidae family.
It is very similar to and very closely related to its sister species the Australian bass, Macquaria novemaculeata. Key differences in estuary perch are that:
- it has a slightly larger mouth and slightly more "scooped" forehead;
- it tends to remain in the estuarine reaches or (more rarely) the extreme lower freshwater reaches;
- it has a diet with more emphasis on small fish and prawns;
- it has a slightly larger growth potential than Australian Bass.
Estuary perch breed in winter at the same time as Australian bass, and the sexual dimorphism possessed by Australian bass and other Macquaria species — of much larger females than males — seems to be present in estuary perch as well. Out of interest, occasionally estuary perch/Australian bass hybrids are recovered; they are presumed to be non-viable.
Female estuary perch reach sexual maturity at older, larger sizes than males.
Estuary perch continue the trend of native fish of southeast Australia being incredibly long-lived. Longevity is a survival strategy to ensure that most adults participate in at least one exceptional spawning and recruitment event, which are often linked to unusually wet La Niña years and may only every one or two decades. Maximum recorded age is 36 years.