The company will be bought in two stages – the first comprising an upfront $50 million payment.
Tassal will also pay a "growth-based earn-out component" through the issuance of new shares to De Costi over three years.
The share component will be in line with the five-times earnings multiple, Tassal said in a statement, and be capped at 10 million new shares.
According to the FinancialReview, Tassal plans to use the acquisition to expand its presence in Australia's A$4.3 billion seafood market.
"The proposed acquisition of De Costi Seafoods will further build on our domestic salmon capabilities, increase Tassal's vertical integration in salmon, drive increased scale and provide Tassal with access to the broader seafood market," Tassal managing director Mark Ryan said.
