In our presentation, we aim to address the following questions: 1) Why do we continue to promote the seaweed industry in Tunisia? 2) What are the challenges that this industry has faced and the responses provided by various research actions? In Tunisia, a research program for the development of seaweed farming started in 1996 but did not lead to the actual initiation of this activity. Seaweed cultivation in Tunisia faces three main challenges: 1) the limited number of suitable species for starting a cultivation activity; 2) the appropriate cultivation technique; 3) understanding the variability of yields and chemical composition. 4) The commercial value of agar is relatively low. The results obtained from research conducted since 1996 at INSTM in the lagoon environment and in the open sea are important for the development of this sector. The cultivation of Gracilaria on the substrate in the Bizerte lagoon, a practice widely used in Asian countries, could be one of the many possible options for the development of this sector by studying the interaction of the cultivated algae and its associated fauna. This technique is only applicable in depths less than 2 m, representing an area of 10% of the entire lagoon. The culture model we have developed is in suspended mode, allowing the cultivation of this species at depths beyond 4 m. However, a significant area between 2 and 4 m remains unusable. Therefore, the idea of developing another technique to cultivate algae in water columns arose. The cultivation of Gracilaria in Bizerte Bay using the suspended mod was a first attempt to initiate the cultivation of this species in the open sea, both in Tunisia and in the Mediterranean basin. In conclusion, the acceptable growth rates and the richness of algae in proteins, phycobiliproteins , and agar in specific culture situations can certainly justify the cultivation of this species of macroalgae . The limited possibilities of the lagoon environment and the high production costs, both in this lagoon environment and in the open sea compared to other countries, encourage us to exploit all the molecules of interest through the development of innovative biotechnology processes such as biorefinery to make its cultivation profitable in the future.