Sea bream and sea bass rearing in Mediterranean countries have undergone significant development since the decade of the eighties. Since then ever increasing productions have led to a considerable fall in prices. Fierce competition on the Italian market, main outlet for both species, together with the recession and monetary crisis worsen this situation. The analysis of the profitability factors of sea farms in the Mediterranean depends on the economic standards taken into consideration. Whilst certain countries benefit from aids and incentives which even finance various farming costs, other countries have to assume extra investment costs, in particular of research or site conditioning. In Morocco, sea bream and sea bass rearing began in 1986. Two rearing systems are currently practised: an intensive system in cages situated in the lagoon and an extensive earthpond system. The following case describes intensive gilt-head sea bream and sea bass production in the Nador Lagoon.