The Department of Conservation says it believes New Zealand's longfin eel is being fished sustainably, but it faces extinction if its numbers keep dropping.
Environmental groups and scientists say the longfin eel is threatened and should not be fished commercially.
The eel is classed as declining and at-risk in the department's table of species, putting it just below threatened.
DoC policy manager, Jeff Flavell, says the difference is that threatened species face imminent extinction while at-risk species face eventual extinction if their numbers continue to decline.
One company, Tegel Foods, is using the eel in some products made for upmarket petfood for Te Puke exporter Addiction Foods. The company plans to seek advice from authorities on whether the eel is threatened and, if necessary, stop using it.