Hoki, a species sourced sustainably from New Zealand, was introduced to the Birds Eye range in 2002 as a white fish alternative to cod, a threatened species.
However, consumers have not bought hoki products in significant numbers, and the product has been withdrawn from sale in supermarkets.
In 2002, Unilever committed itself to sourcing all Birds Eye fish stocks from sustainable fisheries in the UK by 2005. Last year it admitted it was unlikely to hit the target.
Separately, Birds Eye is aiming to reduce manufacturing costs by streamlining the number of product variants in its portfolio from 350 to 300.