An eel spa is not the latest in beauty fads.
Rather it's a spa that is keeping 1400 tiny eels alive in the country's only eel rearing facility at the Foxton Wildlife Trust in Horowhenua.
Muaupoko iwi has set up a highly successful aquaculture programme, which is helping rejuvenate the population of tuna (longfin eel) in Lake Horowhenua, but when the temperature dropped in winter at the facility, so did the eel survival rate.
Robert Warrington has been working on the project since its inception, and was stumped as to why the eels began to die.
"We would get here in the morning and two or three would be dead in the food bowl," he said.
The PH and nitrate levels in the tanks were tested, and even salt added to combat potential fungal infections.
The tests showed the water to be at a "five-star hotel standard", however eels continued to die.
Mr Warrington said that according to information he had read, eels should only be dying of cold if the water temperature dropped below 9 degrees, but the tank water was nowhere near that low.
Due to lack of research around the rearing of such young eels, Mr Warrington thought the information applied to larger eels with fat stores.
"[Our eels] are little and so it's just going to be a different temperature," he said.
"We got the spa pool in there to see if that would help and within seven hours they were all cuddling up in [the spa] and we've had no mortalities [since]."
Mr Warrington and other volunteers continue to keep a close eye on the eels.
"You can tell by the way they are swimming how their health is, but that only comes from watching them for quite a while. I don't actually mind sitting here and watching them," he said.
Last season Mr Warrington caught 5000 elusive glass eels as they entered the Hokio Stream after their sea voyage.
After growing and releasing 300 healthy elvers into Lake Horowhenua, 1370 remain at the aquaculture facility and will continue to be grown over a year before being released, tagged with GPS for further research and study.
Muaupoko's aquaculture programme has yielded a phenomenal 34 per cent survival rate considering only five percent of glass eels reach maturity in the wild.
With an "ambitious" goal of collecting 10,000 for the aquaculture facility, Mr Warrington and volunteers will be out with their nets over the coming weeks.
His ultimate goal is to unite iwi across the country and work together to replace commercial tuna fishing with a large scale aquaculture programme; allowing tuna in the wild to thrive and not be fished to extinction.
Once a daily food source for Muaupoko, the tuna population has taken a massive hit over the 150 years of European settlement, with more than 90 per cent of the tuna wetlands habitat destroyed, and dams and weirs blocking upstream migration of young eels.
Tuna can live for more than 100 years and grow as long as 2m but tuna this size have not been found for more than five decades.
"Tuna's biggest enemy has been farming. Before Europeans came, Horowhenua was a maze of interconnected swamps and through manmade channels, we would farm eels and shell fish inland." Mr Warrington said Muaupoko's once thriving aquaculture and fisheries was the envy of many tribes.
"In Maoridom we say tuna is the kai of the Rangatira but in Muaupoko everyone had one because of our aquaculture."
It takes 40 years for a tuna to reach maturity before it leaves its fresh water home for a perilous sea journey to Tonga's warmer waters, where they breed then die, their eggs floating to the surface to hatch into flat, leaf-like larvae that drift along oceanic currents back to New Zealand.
On arrival, the larvae change into small transparent versions of adult eels, slowly developing colouration before migrating upstream to develop into adults and begin the cycle again. Note to whitebaiters: Please watch your catch carefully.
If you catch glass eels please throw them back or pass them onto Foxton Wildlife Trust, 48 Harbour St, Foxton, 06 363-5300. Thank you to whitebaiters who passed on their eels last season.