The opercula or gill covers possess a small, flat spine sharp enough to cut unwary fishermen's fingers.
The fish has also been successfully introduced to other river systems in the Northern Territory, Queensland, and New South Wales, confusing studies of the natural range.
The taxonomy of golden perch has not been updated to reflect this, although the term Macquaria ambigua oriens, denoting subspecies status, has recently appeared in literature discussing the Fitzroy–Dawson population.
In the Murray River, wild male golden perch generally reach sexual maturity at 3 years of age and 32.5 cm in length, and wild female golden perch at 4 years of age and 40 cm in length.
[9] Golden perch have a flexible breeding strategy but generally (but not always) require a spring or summer flood or "fresh" (temporary, within-channel increase in flow) to stimulate spawning.
[11] Like other Macquaria species, sexual dimorphism is present, with females reaching much larger maximum sizes than males.
Adult fish have been recorded migrating well over 1,000 km when flood conditions allow passage over weirs and other man-made obstructions.
[13] The evidence suggests that before European settlement, huge shoals of golden perch roamed the entire lowland and slope reaches of the vast Murray-Darling River system, unimpeded.
Thus, the gradual loss of fish passage through the numerous dams, weirs, locks, and other barriers (estimated at 4,000 in the Murray-Darling system[14]) now present has had severe impacts on the species.
Longevity is a survival strategy in the often challenging Australian environment which ensures that most adults participate in at least one exceptional spawning and recruitment event.
Wild populations have declined significantly, and a number of populations lost in upper reaches of rivers, due to dams and weirs blocking migration, mitigating floods and freshes, regulating flows, and releasing unnaturally cold water ("thermal pollution"), all of which interfere with migration, spawning, and recruitment.
[4] Golden perch are extremely migratory and migration appears to have been important in maintaining populations over the length of rivers, particularly the upper reaches.