Shellfish: Nature’s marine cleaning service

When we talk about restoring shellfish reefs, it’s not just about creating more fish habitat—it’s also about cleaner, healthier waterways.

Take a look at the video below. On one side, you’ll see a tank of murky water. On the other, the same water after spending time with a cluster of oysters. The difference is clear (literally!): the tank with oysters quickly cleans up, showing just how powerful these little filter-feeders can be.

Shellfish like oysters and mussels are nature’s filtration system. Every day, they draw in water, trap microscopic algae and particles, and spit out cleaner water. A single oyster can filter more than 100 litres a day, and when thousands work together on a reef, the effects can be massive.

This natural cleaning service not only makes the water clearer, but also lets sunlight reach seagrass and kelp, in turn providing even more habitat for fish. It also helps recycle nutrients like nitrogen and phosphorus, which, if left unchecked, can fuel algal blooms. By feeding on excess nutrients, shellfish play a direct role in keeping our coastal ecosystems balanced.

Recent experiments with OzFish’s Robust Oyster Baskets (ROBs) have shown just how powerful this can be, with initial results suggesting a single reef module can filter thousands of litres of water a day. Multiply that across a restored reef, and you’re looking at a serious boost to waterway health.

In short: more shellfish means cleaner water, healthier habitats, and better fishing. It’s why shellfish restoration is featuring in recovery plans for South Australia right now, and why other states should be looking at it too.

Learn more about OzFish’s Shellfish Revolution program, with projects right across Australia.