A Strange Subject to Write About - The Positive Impact of Fish Poop

Before I talk about the main topic, I want to share with you that I just did the Keynote last week for the Pennsylvania Assisted Living Association on Increasing Your Leadership Power to New Levels of Excellence and 82% of the attendees rated it as Excellent! 

Please let me know if you have any group or organization you’d like me to contact about speaking at their meetings and conferences. Thanks for considering this.

So now for the topic of this week’s blurb:

Coral reefs are some of the most diverse and vibrant ecosystems on the planet, providing a home for a vast array of marine life. While many factors contribute to the health and resilience of these ecosystems, one often overlooked component is…did you guess it? - fish poop. Yes, you read that right – fish poop actually plays a crucial role in maintaining the delicate balance of coral reefs.

Nutrient Cycling

Coral reefs are actually nutrient-poor environments, with limited availability to access essential nutrients like nitrogen and phosphorus. Fish, being an integral part of the reef ecosystem, consume algae, plankton, and small invertebrates, which are rich in these nutrients. As they digest their food, they excrete their waste in the form of poop, which is rich in ammonia, nitrate, and phosphate which makes their poop a natural fertilizer.

The corals then rely on the nutrients from this fish waste to build and maintain their complex structures. The nutrients from fish poop also support the growth of algae, which in turn provide a food source for herbivorous fish, creating a self-sustaining cycle.

Stimulating Coral Growth

Studies have shown that the presence of fish poop can stimulate coral growth, with some species of coral growing up to 30% faster in the presence of fish waste. 

In one coral bleaching event that occurred in 2016, the researchers saw the corals regrow more than twice as quickly and recover 10 months sooner when their corals had a supply of poop that came from an area that was crowded with seabirds on its shores. 

These sea birds when they are in an especially in large colonies of, for example, 280,000 breeding seabird pairs drop guano or bird poop on the reef which does the same thing as fish poop in terms of stimulating the reef’s growth. 

All of this happens because fish and bird poop helps to promote the growth of coral polyps, which are the building blocks of coral colonies.

Additionally, the increased nutrient availability from fish poop can also lead to an increase in the coral's skeleton density, making them more resilient to environmental stresses like ocean acidification and warming.

Maintaining Reef Diversity

Fish poop also plays a crucial role in maintaining the diversity of coral reef ecosystems. By providing a source of nutrients, fish poop supports the growth of a wide range of marine plants and animals, from sea fans and sea whips to sponges and other invertebrates.

This, in turn, supports a diverse array of herbivorous and carnivorous fish, which help to maintain the balance of the ecosystem. By keeping algae growth in check, herbivorous fish prevent the overgrowth of algae, which can outcompete corals for space and resources.

So as I said, this is a strange topic to discuss but an important one as the oceans continue to heat up. By providing a natural source of nutrients, fish poop and bird poop supports the growth and diversity of coral reefs, making them more resilient to environmental stresses.(Reported Audubon, Spring 2025)