There is a kind of fish that sends saltfly fishermen into orbit just thinking about it. They salivate, and their eyes roll when the word is mentioned. It is a bonefish.

We should first explain the term "saltfly". It is a fly fisherman who has adapted trout gear to fishing in the sea. The tackle is the same as that used for trout fishing, but is heavier so it can handle larger, more powerful fish. And the reel is stronger with a more robust drag system.

Otherwise the technique is the same - cast out the fly and retrieve it.

Saltfly fishing was born in Florida about 50 years ago, but some people had been taking their trout rods out to sea for fun before then, and we used to do exactly that while snapper fishing out of Whakatane.

We would cast silver smelt flies at schools of kahawai and trevally and, when hooked, these fish - which were about the same size as the trout we caught in Rotorua - would make the trout look like a snail compared with a racing lizard.

But trout do have other values, a delicacy that no salty thug can ever emulate.

The appeal of the bonefish, which is responsible for kicking off serious saltfly sport, is its lifestyle. They live in deep water but feed on shallow flats, moving in with the rising tide and grubbing around in the sand for worms and shrimps. The water where they are found is generally clear as gin, and the "bones" can be spotted on the Florida flats as their tails wave out of the water. The locals call it tailing. It is visual fishing, a bit like hunting. The angler spots his quarry, stalks it and endeavours to cast a fly to it without spooking it.

Bonefish are sometimes called "grey ghosts" because they appear as pale shadows in the clear tropical water - and they have plagued my personal attentions for a long time; more than 25 years, to be exact.

My first attempt was in the mid-1980s on the Florida Keys, with world saltfly record-holder Billy Pate. Now if you can't catch a bonefish with the best saltfly angler in the world, there is something wrong.

There was something wrong. "Every bonefish here has been caught and released many times. They are the smartest bonefish in the world," said Billy. We saw some tailing as they grubbed in the sand with tails waving on the surface, and they saw us and were gone in a flash. However, we did catch and release several 45kg-plus tarpon on the fly rod. That was serious adrenalin-fuelled excitement. But no bones.

This is such big business in Florida that the local chamber of commerce commissioned a study on the value of the fishery to the local economy, taking into account the expenditure by bone-hunting visitors including travel, guiding, accommodation and so on. It concluded that each individual fish was caught an average of eight times in its life - they are always released - and was worth about US$16,000.

In this part of the world, you can find bonefish around many of the tropical atolls which have shallow lagoons. Once in the Cook Islands, while standing in knee-deep water in the lagoon at Aitutaki and casting a fly for trevally, a huge bonefish sidled up to the fly, spotted me at the other end of the rod and was gone. The French versions at New Caledonia proved similarly elusive, just like their cousins in Tahiti.

And so the quest continues.

It has been suggested by a certain young member of the family who has been on some excursions - with camera held ready to record the magic moment - that bonefish actually don't exist; that they come under the category of imagination figments; and the search will never be fulfilled. Maybe that is the way it should be. Perhaps it will be an anticlimax if a bone ever succumbs to our casting - it is all about the journey not the ending, to quote another hackneyed adage.

What a pity we have no bones in our waters. It is too cold and we don't have the wide, shallow flats. But we could learn a lesson. We have plenty of kahawai and trevally, and saltfly enthusiasts from all over the world would love to come here and cast to them.

Each individual fish would certainly be worth more in this context than as cold fillets in a supermarket. And they can be caught again and again.