Salmon farming has grown to be a highly successful sector in Norway. With the emergence of salmon farming commercial attention has also been brought to other farmable species. Cod farming emerged first during the eighties but it turned out that the innovation system was incapable of creating enough knowledge because there was little interaction between the actors. Today the cod farming sector is once again emerging. The firm structure in the sector is however fragmented. This paper focuses on heterogeneity in the cod farming sector by focussing on the interactive learning processes firms take part in. First by pointing to the environment that firms may interact in. Secondly, by analysing three firms interaction processes with this environment. It applies two ideal typical learning modes. This is learning by doing, using and interacting (the DUI-mode) and learning through science, technology and innovation (the STI-mode). I find that the firms develop different learning processes and accumulate knowledge in along different paths. The first firm is possible developing a lock in. The second is following a first mover dynamics, while the third firm has entered a massive learning phase. Policy implications are made.