A NEW Zealand fish-processing company has been fined after two employees suffered severe frostbite while unloading fish from boat holds filled with subzero-degree water.

One employee was hospitalised for two-and-a-half weeks after he noticed his two of his fingers had turned black during a shift at Mount Maunganui fish processing company, Pelco, in July 2012.

The employee was unloading fish from holds containing water chilled to about -17C.

Eight months later, he is yet to regain movement in his right hand, with his fingers swollen and his joints locked in a fixed position.

Another employee also suffered frostbite and has since recovered from his injuries.

He is now unable to work in cold conditions.

On Tuesday, Pelco was fined $NZ16,000 ($A13,274) in Tauranga District Court for failing to take all practical steps to ensure the safety of its employees.

Both employees had minimal experience and wore thin rubber gloves and cotton glove liners but had torn their gloves on fish spikes,

The tears allowed extremely cold water to seep into their gloves.

Pelco did provide a safety briefing but Maritime New Zealand (MNZ) says it did not specifically identify the dangers of working in extremely cold water.

MNZ regional compliance manager central Pelin Davison said just providing safety equipment is not sufficient.

"This sentence sends a strong message that health and safety is something which must be taken very seriously by employers," he said.

Pelco was also ordered to to pay $NZ4000 to the employee with the most severe injuries and $NZ2000 to the other employee.

Those payments are on top of $NZ10,000 already paid to the employees.