Antimicrobial activities of different metal nanoparticles such as gold, sulphur, selenium, silver, copper, zinc, iron, TiO2 and magnesium oxide were studied with different bacterial and fungal isolates/strains of aquaculture importance. Among them zinc oxide, copper oxide, iron oxide, aluminium oxide, silver, silver -titanium dioxide, magnesium oxide, gold, selenium and sulphur nanoparticles showed broad spectrum antibacterial and antifungal activities. Similarly, Metal nanoparticles such as zinc oxide, copper oxide and selenium showed antialgal properties.