It's a tale familiar to fishermen all over the world - the catch never seems quite as big as it was when anglers were swapping stories at the pub.
Scientists at the Museum of New Zealand were left with a bit of a damp squib last night as their three-day thaw of snap-frozen 495kg colossal squid tonight turned out to be only 4.2 metres long.
It was a long way short of the 10m estimated by longliners on the vessel, San Aspiring, when they hauled it to the surface, gnawing on a 30kg toothfish hooked 1800m under the icy Ross Sea.
Early interviews with the skipper of the Nelson trawler produced an estimated length of 10m.
At the time, Fisheries Minister Jim Anderton breathlessly announced " it is likely that it is the first intact adult male colossal squid to ever be successfully landed" and said the species were estimated to grow up to 12 to 14 metres long.
The thawed colossus of the deep last night turned out to be a little shorter, and female.
"The two long tentacles that the fishermen observed have shortened and shrunken considerably post mortem, giving a final total length of 4.2m," museum worker Chris Paulin said on the museum's "squid blog".
Even as recently as Monday, when the specimen snap-frozen into a metre-wide ice cube was brought out to thaw, scientists were estimating it would be 6m to 8m long.
But they were still thrilled with measurements of the main part of the half-tonne specimen's body, known as the mantle, which showed it was similar to a 2.5m length recorded for an immature female at the museum in 2003.
The squid - which some jokers have suggested should be named "Thor" - weighed 195kg heavier than the 2003 example, which had a total length of 6m.
"These are incredibly plastic animals, and dimensions obviously change considerably," said Mr Paulin, the projects manager at the museum.
But a key indicator of size in the species - the hard "beak" with which it chops 2m Antarctic toothfish into bite-sized fishy chunks - does not shrink. Yesterday's measurements showed a the standard "rostral" length of the beak was 41 mm, compared with 37mm for the 2003 female.
"Beaks up to 49mm have been found in sperm whale stomachs ... this animal must attain much much bigger sizes than this," said Mr Paulin.
Earlier in the day, size did matter when the team found the animal kingdom's biggest eye.
Two Swedish professors specialising in vision in invertebrates, Eric Warrant and Dan Nilsson, measured the squid's eye at 27cm across: "This is the largest eye ever recorded in history and studied," said Prof Warrant, of the University of Lund. If the squid had been alive, the eyes would probably have been 40cm across, "about the size of a beach ball."
"The massive size of the eye indicates the animal is very visual," he said.
A "huge" lens the size of an orange captured a lot of light in the darkness of its hunting grounds more than thousand of metres below the surface of the Southern Ocean around Antarctica.
"They're larger than dinner plates - they're truly fantastic eyes," said marine biologist Dr Steve O'Shea, a squid expert at Auckland's University of Technology.
"I think they will be entirely visual predators with eyes like that, and the lens was truly phenomenal".
The specimen was also found to have not only the very thin skin found on the giant squid (Architeuthis dux), but also a gelatinous layer under that. One researcher said the slightly dimpled texture to the outer layer suggested the squid was evolved for speed.
Dr O'Shea has speculated that it is possible that colossal squid grow to up to 750kg.
Such a specimen would be likely to wrest the title of world's biggest invertebrate from the giant squid.
Several measurements can be used to compare squid of different species, but most scientists focus on the length of the squid's body - its mantle - rather than total length - and this standard measure rarely exceeds 2.25m in giant squid, which may also have two long tentacles up to 13m long. The problems of comparing overall length can be seen from a giant squid - washed up at Wellington's Lyall Bay in 1887 - which was measured at 16.8m, probably after its tentacles had been stretched like rubber bands.
Regardless of the latest colossal squid's length, the 10 scientists working on it last night were still thrilled with its good condition: only about 11 specimens bigger than juveniles have been reported since 2005, and some of those were recovered partly digested from the stomachs of sperm whales.
Watched by thousands of people in an internet broadcast, the last thing the researchers did last night was to gently ease the squid into a good correct shape and "fix" it with formalin injected directly into the thick tissues of the tail fin, the arms and the mantle cavity, where the internal organs are.
They topped up the 7000 litre tank with drums of formalin to soak the squid in a preservative solution, so that it can be displayed at the museum later this year.