NOVELTY - Reducing algal biomass in a body of eutrophic water, involves introducing several organisms that feed on algae to a body of eutrophic water, and culturing the organisms in the eutrophic water, where the organisms are confined to an enclosure or a substrate, and where the organisms feed on the algae, thus reducing the algal biomass.    USE - For reducing algal biomass in a body of eutrophic water (claimed) found inland or in coastal areas, including lake, river estuary, continental shelf, lagoon, drowned river bed, embayment, gulf, and coastal plain, and for reducing the loss of seagrasses and/or perennial benthic macroalgae in an aquatic area.    ADVANTAGE - The method has ability to reduce the algal biomass in a preexisting algal bloom, harmful algal bloom, or hypoxic zone. The algae can be removed efficiently by the organisms. The method pertains to the use of tertiary consumers of planktivorous organisms (predators or piscivores) to facilitate easier and cost effective harvesting of the algae bloom indirectly. An advantage of the method is the flexibility of its deployment in almost any location where there is a body of eutrophic water and at any time of the year. Because the fishes and shellfishes are confined to the systems, they can be readily removed from the eutrophic water. Thus, the presence of the fishes and shellfishes in an eutrophic zone is not necessarily persistent.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) producing biofuel and/or fish meal, involving introducing several fishes that feed on algae to a body of eutrophic water, where the fishes are confined to an enclosure, culturing the fishes in the eutrophic water where the fishes feed on the algae, harvesting the fishes from the enclosure, and processing the harvested fish to produce biofuel, specialty chemicals, nutraceuticals, food, and/or fish meal;    (2) a system for reducing algal biomass in a body of eutrophic water, comprising several organisms that feed on algae in a body of eutrophic water, where the organisms are confined to an enclosure in the body of eutrophic water.