Aquaculture can have negative environmental impacts if not properly managed. Large amounts of uneaten fish food, fish excrement, and chemicals used in aquaculture can deplete oxygen in water, create algal blooms, and contaminate shellfish. These effects harm ecosystems and can pose health risks. However, the impacts of aquaculture can be reduced by using specialized fish feed, raising fish with other organisms to filter waste, minimizing the use of chemicals, and properly disposing of farm waste.