They are slippery and slimy but demand for these snake-like fish is growing fast.

A Tasmanian family is exporting hundreds of short-finned eels out of the state each week.

Five years ago, the Finlaysons were exporting five tonnes. In 2014 they sent 64 tonnes to America, Canada, South Korea, Japan and China.

"The demand has risen, it's changed a lot," Shaun Finlayson said.

"We originally started with a China focus to grow but we've changed the focus away from China and are sending more to countries like Canada and America, where they have high populations of Chinese in places like Toronto and New York.

"These Chinese nationals like food to remind them of home and we've found them to be quite lucrative markets. They take the volume and they can afford the prices."

The Finlaysons have been in this slippery business for 50 years and three generations.

They have seven geographically based licences, allowing them to catch eels in countless farm dams and lakes across the state.

Each expedition involves at least two days' work: one to set up the nets and another to pick up the catch.

"We camp away a lot and sleep in our swags a lot, you might find us in parks or beside a river something like that or on farmers' properties, so we do some pretty big days and that runs for maybe nine months of the year," Brad Finlayson said.

In a good week they will pull two tonnes from several waterways using special tunnel-shaped nets.

"The way that we set our nets from the shores out to the deep is solely so that we don't use any bait or any other artificial way," Brad Finlayson said.

"They are cruising round the shores looking for a feed and they go into the nets and then once they do get a feed they go back and sit in the mud and rest in the weed until they are ready to go for another feed."

Ninety per cent of the fish they catch are Tasmania's most common eel, the Tasmanian short-finned, which are prized in Asia for their wild eel taste.

They grow slowly and are older and tougher than the Asian-farmed eels which are grown out in ponds.

The average weight of the short-finned eel is about 600 grams, although they can top one kilogram.

Brad Finlayson pulling in a net of eels on a lake in northern Tasmania. ( Supplied: Brad Finlayson )

Dams block migration of eels

Even before they are caught and exported overseas, Tasmania's eels clock up a lot of travel miles.

Researchers believe adults swim from Tasmania to the depths of the Coral Sea to spawn and die and their larvae ride the currents back.

The only hiccups along their path are the numerous dam walls built by Tasmania's hydro-electricity industry.

"As the currents come down they smell the fresh water and make their way up the river systems," Brad Finlayson said.

"Unfortunately due to the hydro system they can't get over the dam walls due to the size of walls."

Hydro Tasmania and the state's Inland Fisheries joined forces to give the eels a helping hand up over the walls into the hydro catchments.

Last season, almost 300,000 elver — young eels — were relocated over the walls to rivers, lakes and dams.

"We get them from two locations in Tasmania and one side is the Trevallyn tail race just outside of Launceston and we use the fyke net method there; and the other location is in the south, the base of Meadow Bank dam," Brett Mawbey from Tasmania's Inland Fisheries said.

Brad Finlayson in his boat. ( Supplied: Brad Finlayson )

The Finlaysons also do their bit to boost stocks across the state, buying thousands of elver from Inland Fisheries to build up populations in farm dams.

"Once we purchase the fish off Inland Fisheries and relocate them, our investment is for a long-term goal, we won't see these fish for another 10 years," Brad Finlayson said.

"In aquaculture, we could reduce that by four to five years and it's something the family is looking at."

The Finlaysons are hoping to develop a system of heated ponds with circulated water, keeping the water temperature up to increase growth.

If the family's aquaculture plans are given the green light, they hope to be exporting up to $10 million worth a year by 2020.

"As we all know, the salmon industry has been a big player in that industry, down the track in time ... the eel industry will be a big player," Mr Finlayson said.

"Tasmania is quite lucky because we have the number of eels in the state that we can actually do this.

"All we need to do is make sure we get it right and get it so we can make a dollar out of it, but also we can employ people in the state."