Then he jumped in the kayak and after half an hour managed to net the fish.
“When I took it out, I realised it was at least 30 centimetres long.
“It wasn't big, it was bloody big.”
They rushed the fish home and it lives on today in the Walker's fish pond — the biggest goldfish in there by far.
Theories of what it is, and how it got there, have ranged from a former pet left to grow huge, to a surviving fish from when the botanical garden ponds were flushed out about 10 years ago.
Other sightings of goldfish in the river by Campion College were recorded a few years ago.
“I don't know whether it is a giant goldfish or a carp,” said Tony.
“We've been living on this river bank for 15 years and never seen anything like it. It is like a goldfish on steroids.”
The Taruheru River by their property is brackish water — which is where fresh water meets salt water, but Tony says it is mostly freshwater.
Department of Conservation community ranger Jamie Quirk said the fish was “most probably” a goldfish as carp have barbels on their lower jaw.