Following the story about a monster Murray River cod pulled from a Canning Vale lake last week, Perth's urban fishing community has weighed in with another "tail" to tip the scales.
Clay Anderson of Langford sent in a photo of an 83-centimetre, eight-kilogram carp caught in a similar man-made lake at Tom Bateman Reserve in Thornlie last year.
Over the years, Mr Anderson reckons he's caught "hundreds" of carp at the unassuming spot – though he admits it is likely he's caught the same kind of fish over and over.
"I put most of them back, because they're not going anywhere," he told Fairfax Media.
A keen Swan River fisherman, Mr Anderson's curiosity was first piqued two years ago when he saw someone sitting patiently by the lake, rod in hand.
"I saw him a few times and wondered what the hell he was doing, so I went down there and tried myself and have been pulling them up ever since," he said.
The secret to catching carp was a piece of bread on a small hook with a tiny sinker, he said.
"They're easy to catch because they're everywhere," Mr Anderson said.
"Rumour has it that when the council was building the lake, some of the locals decided to fill it with carp.
"It gets quite busy with fishermen over the weekend."
But it's not just drains and lakes around Perth's south-eastern suburbs that are full of foreign species: Mr Anderson claims they're everywhere, and have built up quite a following amongst urban fisherfolk.
"I've seen carp caught all over Perth," he said. "They're getting them in Lake Monger, Emu Lake and everywhere.
"There have even been a few caught in the upper reaches of the Canning River.
"A lot of the fishermen are Poms [British] or Asians, who are used to fishing for carp in their own waters.
"Some even take the fish home to eat - but you won't get me doing that!
"That's all grey water from drainage - the fish are probably all full of mercury."
Murdoch University freshwater fish researcher Stephen Beatty said he "wasn't surprised" to learn of Perth's urban fishing community and their exploits.
"We've caught [carp] up to that size as well," he told Fairfax Media.
"It's a little bit disappointing, really, that people have been putting these invasive species in – we'd be far better off if people put native fish in there.
"But I understand that quite often a lot of these introductions are from a lack of understanding of the impacts these things can have."
Dr Beatty said foreign fish species now outnumbered native species in WA's south-west waterways by 14 to 11.
"Most new species are from aquariums," he said. "And despite what people think, they can still get into river systems during floods etc.
"Eradicating them is almost impossible once they're up and breeding."
Dr Beatty said carp were an especially destructive species.
"They stir up sediment and release nutrients which is no good for algal blooms," he said.
"It's also the things you can't see, like disease and parasites, that can have the most damage."
The most common introduced fish species in South West WA is the gambezi, which is known to aggressively attack native species by pecking their fins off.
It's arguably the "cane toad" of invasive fish species as it was introduced by the government in the 1930s to control mosquito populations – hence it's nickname, "mosquito fish".
