The golden perch (Macquaria ambigua) is an Australian native freshwater fish. It is a member of the Percichthyidae family. The Golden perch derives its scientific name from the Macquarie River where the first scientifically described specimen was collected (Macquaria). (Richardson marked the specimen as having been collected from a marine environment.)

These fish are also commonly known as "Callop" (particularly in South Australia), and can easily be distinguished from Silver Perch by a much larger mouth and pronounced hump on their head (in the latter stages of Juvenile life).

Golden perch are a medium sized fish, commonly 30–40 cm and 1–2 kg in rivers. Golden perch can vary greatly in shape and size. Fish from rivers are smaller and somewhat streamlined . Fish in man-made impoundments are much deeper-bodied and show much greater average and maximum sizes. Golden perch have been recorded up to 9 kg in rivers, and up to 15 kg in impoundments.

Golden perch have a distinctive concave forehead with a protruding lower jaw and truncate caudal fins, the humped back appearance increases with age.

They vary in colour from bronze, olive or brownish all over with a yellow to white underside. Median fins are grey-black, while paired fins are dusky grey to yellowish. Juveniles are silvery with scattered grey mottling on the sides and dusky grey fins.

The Golden perch (yellowbelly) are found naturally in four Australian river basins.
Linked maps are listed to view Golden Perch (Macquaria ambigua) in their natural range.

Average gene-flow statistics, FST = 0.760 and Nem=0.08, suggest that the populations in each of the four basins can be regarded as separate gene pools that have been isolated for different, and considerable, periods of time (Australian Journal of Marine and Freshwater Research).

Golden Perch have also been widely Introduced to many other coastal systems in Queensland and New South Wales

Golden perch are predominantly found in the lowland, warmer, turbid, slow flowing rivers. In rivers when water current is still they tend to sit on or close to snags (fallen trees) or rocky outcrops. In rising waters or flooding events fish will form large schools and enter into very turbulent or fast flowing waters when trying to migrate upstream.

Records have shown that Golden Perch tagged at Loxton in South Australia have been recovered at Mungindi on the New South Wales-Queensland border, more than 2000 river kilometers away (Victorian Department of Natural Resources and Environment).

A very tolerant fish reported to withstand water temperatures of 4 to 37°C, and salinities up to 33,000 parts per million (almost that of sea-water).

Golden perch are predators, eating mainly shrimps, small yabbies, benthic aquatic insect larvae, mollusks, frogs, small fish and aquatic invertebrates. Feeding behavior varies; some individuals remain in shaded areas or amongst cover to take prey as it passes, whilst others move slowly over weed beds etc. to feed. Juvenile fish consume more of the smaller items such as aquatic insect larvae and micro crustaceans.

Golden perch or yellow belly as they are more commonly known, are a good fighting fish, they are vigorous takers of both bait and lures.
Early morning and evening are the best times of the day. When the water is rising you can catch them almost anywhere on the river bank.
When water isn't rising - cast your bait in close to snags (fallen timber, rocky outcrops or any underground structure, where they might hunt under cover).
Bibbed lures and spinner baits are worth trying.
A running sinker works well with some people, and sinker on the bottom will work well for the fisherman who generally fishes this way. Shrimps, worms and small yabbies are the most popular baits, and hungry perch will take prawns if the other 3 are unavailable.

This is a precious fish - so please fish by the rules!!!
It’s important to know the rules that apply to fishing. These include bag limits and minimum size limits for different types of fish. A bag limit is how many fish you are allowed to keep in one day. A minimum size limit is how big a fish needs to be in order for you to keep it.

Excellent eating fish - A white flesh with a mild, light and delicate taste. It has a moist medium to firm texture, which holds its shape when cooked.
Golden perch are very good fried, steamed or baked.

Wild populations have declined significantly, especially 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. Golden perch are extremely migratory and migration appears to have been important in maintaining populations in some reaches of river, usually the upper reaches.

Weirs are proving to be a more significant threat to golden perch than first thought, with a recent studying proving that about 90% of golden perch larvae passing through undershot weirs are killed (Baumgartner et al., 2006).

The species is however bred in hatcheries in large numbers and stocked. Concerns over genetic diversity issues are growing however.