The note, which will replace its more bland predecessor from September 1, features a yellow Prickly Moses wattle flower and a colourful Eastern Spinebill native bird.
"Each banknote in the new series will depict a different species of Australian wattle and a native bird within a number of the elements," Reserve Bank of Australia governor Glenn Stevens said in a statement.
"The designs are the culmination of a process of extensive consultation with subject-matter experts and the cash-handling industry, as well as qualitative research involving focus groups."
"Our new fivers look like vomit," one user wrote on Twitter, while another quipped: "A thousand monkeys with a thousand versions of Photoshop could never come up with something as hideous as the new Australian USD 5 note."
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Some questioned why the same portrait of Queen Elizabeth II, which was drawn from photographs commissioned by the central bank in 1984, was used rather than a recent image of Australia's head of state.
"New Australian USD 5 note really knocks years off the Queen," tweeted Joanna Hall.
"It's way off in terms of colouration," Birdlife Australia's migratory shorebird programme manager Dan Weller told AFP, although the bird's shape and markings were fairly accurate.
"The way it's been shown on the note, the only two colours that are right on there are the black and the white."
Eastern Spinebills -- found on Australia's east coast -- have red eyes, black heads, grey wings and tails, white throats, and chestnut-coloured undersides.
But the new bill gives them a bluish underside with a bright blue, yellow, purple and pink wing.