why would too much algae pose a risk to fish?

Too much algae poses a risk to fish primarily because dense algal blooms deplete oxygen levels in the water, causing fish to suffocate. Algae consume oxygen during nighttime or when they die and decompose, and this oxygen depletion can create "dead zones" where fish and other aquatic life cannot survive. Additionally, some types of algae produce toxins that can damage fish gills, cause organ damage, and even lead to fish death. The overcrowding of algae also blocks sunlight, harming underwater plants that supply oxygen and food for fish, further disrupting the aquatic ecosystem.