Despite its healthy growth, the aquaculture industry still faces problems with diseases which can affect its sustainability. Infectious diseases caused by bacteria, fungi and viruses are continuing threats to consistent industry growth. The heavy use of antibiotics could be detrimental to the health of fish. This practice encourages the evolution of resistant pathogenic strains. Nowadays researches on a worldwide basis have paid attention towards the potential of marine microorganisms as an alternative source for isolation of novel metabolites with interesting biological and pharmatheutical properties . Marine fungi have been recognized as an important resource for novel bioactive compounds. A greater development of marine biotechnology will produce novel compounds that may contribute significantly towards drug development over the next decade. The current work will try to elucidate the most common fish diseases and the adverse effect of the extensive uses of chemical drugs for treatment. Moreover, the bio-control using marine fungal metabolites as antimicrobial, cytotoxic and anti- fish pathogenic agent(s) was found to be both prophylactic and curative.