Green mussels and Hong Kong oysters are significantly better at cleaning polluted water than other shellfish species, removing 40-54% of major pollutants within 96 hours according to Gram Research analysis. In a controlled study, green mussels removed 53.6% of ammonia and 39.67% of suspended solids, while Hong Kong oysters removed 40.3% of suspended particles. These species work best at specific temperatures and salt levels, making them promising candidates for naturally filtering polluted aquaculture water.
Scientists tested five types of shellfish to see which ones are best at cleaning polluted water. According to Gram Research analysis, two species, green mussels and Hong Kong oysters, stood out as champions at filtering out harmful nutrients and waste. After 96 hours in polluted water, green mussels removed over half of ammonia and nearly 40% of suspended particles. The research shows these shellfish could be valuable tools for cleaning up aquaculture farms and polluted waterways, especially when kept at specific temperatures and salt levels that help them work their best.
Key Statistics
A 2026 research study found that green mussels removed 53.6% of ammonia from polluted water within 96 hours, significantly outperforming four other shellfish species tested under identical laboratory conditions.
According to 2026 research on five bivalve species, green mussels and Hong Kong oysters had filtration rates of 0.92 and 0.85 liters per hour per gram of body weight, with assimilation efficiencies of 88% and 82% respectively, compared to much lower performance in three other species.
A 2026 study of shellfish water-cleaning ability found that green mussels removed 45.75% of phosphate and chemical oxygen demand from eutrophic water, while Hong Kong oysters removed 40.3% of suspended solids in the same 96-hour period.
Research published in 2026 demonstrated that green mussels maintained optimal water-filtering performance at temperatures between 21°C and 31°C with 30 parts per thousand salinity, while Hong Kong oysters preferred cooler, less salty conditions at 21 ppt salinity and 6-8 mg/L dissolved oxygen.
The Quick Take
- What they studied: Which types of shellfish are best at filtering pollutants out of water, and what conditions help them work most effectively.
- Who participated: Five species of bivalves (shellfish): green mussels, Hong Kong oysters, Sika oysters, clams, and another clam species. They were exposed to artificially polluted water for 96 hours.
- Key finding: Green mussels removed 53.6% of ammonia and 39.67% of suspended solids, while Hong Kong oysters removed 40.3% of suspended solids. Both species significantly outperformed the other three types tested.
- What it means for you: If you live near aquaculture farms or polluted waterways, these findings suggest that farming these specific shellfish species could naturally clean the water. However, this is early-stage research and would need real-world testing before widespread use.
The Research Details
Researchers selected five different shellfish species commonly found in Asian waters and placed them in tanks with artificially created polluted water. The water was designed to mimic conditions in overfed fish farms, where excess nutrients cause problems. After 96 hours (4 days), they measured how much of various pollutants the shellfish had removed from the water.
They also studied how efficiently each shellfish species processed food and nutrients. This included measuring how much water each shellfish could filter per hour, how much of the food they ate they actually absorbed, and how much they consumed. Finally, they tested different water conditions, like temperature, saltiness, and oxygen levels, to find the sweet spot where each species worked best.
Understanding which shellfish are best at cleaning water and what conditions they need is important because polluted water from fish farms damages ecosystems. If we can use shellfish as natural filters, it’s cheaper and more environmentally friendly than mechanical cleaning systems. This research helps identify which species to use and how to set up the best conditions for them to work effectively.
This study tested five species in controlled laboratory conditions, which is a good starting point. However, the sample size is small, and real-world conditions are more complex than a laboratory tank. The research was published in a peer-reviewed journal focused on water quality, which adds credibility. The specific measurements and percentages provided suggest careful data collection. Readers should note that laboratory results don’t always translate perfectly to natural environments.
What the Results Show
Green mussels (Perna viridis) were the clear winners in cleaning polluted water. In just 96 hours, they removed 53.6% of ammonia, 45.75% of phosphate, 39.67% of suspended particles, and 45.75% of chemical oxygen demand (a measure of organic pollution). Hong Kong oysters came in second place, removing 40.3% of suspended particles and 19.75% of both phosphate and chemical oxygen demand.
The other three species, Sika oysters, clams (Meretrix lyrata), and another clam species (Cyclina sinensis), performed significantly worse, removing much smaller percentages of pollutants. Green mussels and Hong Kong oysters also showed superior feeding efficiency, meaning they processed more food and absorbed more nutrients from what they ate compared to the other species.
When researchers looked at the efficiency of how these shellfish worked, green mussels and Hong Kong oysters had clearance rates (the amount of water they could filter) of about 0.92 and 0.85 liters per hour per gram of body weight. They also had very high assimilation efficiency, meaning they absorbed 88% and 82% of the food they consumed, respectively. This is important because it shows they’re not just filtering water, they’re actually processing and absorbing the nutrients effectively.
Larger shellfish with bigger shells filtered more water than smaller ones, suggesting that size matters for water-cleaning ability. The research also found that green mussels performed best at temperatures between 21°C and 31°C (about 70°F to 88°F) and in water with 30 parts per thousand salinity. Hong Kong oysters preferred less salty water (21 parts per thousand), higher oxygen levels (6-8 mg/L), and slightly alkaline conditions (pH 8.1). These specific preferences are important for anyone wanting to use these shellfish in real-world applications.
This research builds on existing knowledge that shellfish are natural water filters. Previous studies have shown that oysters and mussels can improve water quality, but this study is valuable because it directly compares five species side-by-side under identical conditions. This makes it easier to identify which species work best. The findings align with what scientists already knew about shellfish being effective bioremediators, but provide new specific data about which species excel and what conditions optimize their performance.
The study was conducted in laboratory tanks with artificially polluted water, not in real oceans or farms. Real-world conditions are messier and more variable. The researchers didn’t specify exactly how many individual shellfish they tested, which makes it harder to judge the reliability of the results. The study only lasted 96 hours, so we don’t know if the shellfish would maintain this cleaning ability over weeks or months. Additionally, the research doesn’t address potential downsides, like whether using these shellfish might introduce other problems or whether they could escape and affect local ecosystems.
The Bottom Line
Based on this research, green mussels and Hong Kong oysters show strong promise as natural water filters for aquaculture systems (confidence level: moderate). If you’re involved in fish farming or water management, these species are worth investigating further for your specific situation. However, this is laboratory research, and real-world testing is needed before large-scale implementation. Consult with environmental scientists and local authorities before introducing non-native species to your area.
Aquaculture farmers dealing with water quality problems should pay attention to this research. Environmental managers responsible for polluted waterways might find this useful. Researchers studying water treatment and ecosystem restoration should consider these findings. People living near fish farms or concerned about water pollution in their area may find this encouraging. However, this research is too preliminary for home aquarium enthusiasts or small-scale operations without expert guidance.
In a laboratory setting, these shellfish showed measurable water improvement within 96 hours (4 days). In a real-world farm or waterway, results would likely take longer due to larger volumes and more complex conditions. You might see noticeable improvements within weeks to months, but establishing a stable, self-sustaining system could take several months to a year. Results would depend heavily on water volume, shellfish density, temperature, and other environmental factors.
Frequently Asked Questions
Which shellfish species is best at cleaning polluted water?
Green mussels (Perna viridis) are the most effective, removing 53.6% of ammonia and 39.67% of suspended solids within 96 hours. Hong Kong oysters rank second, removing 40.3% of suspended solids. Three other tested species performed significantly worse.
How long does it take shellfish to clean polluted water?
In laboratory conditions, green mussels and Hong Kong oysters showed measurable improvement within 96 hours (4 days). Real-world results would likely take longer depending on water volume, shellfish density, and environmental conditions.
What water conditions do these shellfish need to filter effectively?
Green mussels work best at 21-31°C temperature and 30 parts per thousand salinity. Hong Kong oysters prefer 21 ppt salinity, 6-8 mg/L dissolved oxygen, and pH 8.1. Larger shellfish filter more water than smaller ones.
Can I use these shellfish to clean my fish farm or pond?
This research shows promise, but it’s laboratory-based. Before using these species in your system, consult environmental experts about local regulations, potential ecological impacts, and whether these species are appropriate for your specific water conditions and location.
How much of the pollutants do these shellfish actually remove?
Green mussels removed 53.6% of ammonia, 45.75% of phosphate, 39.67% of suspended solids, and 45.75% of chemical oxygen demand in 96 hours. Hong Kong oysters removed 40.3% of suspended solids and 19.75% of phosphate and chemical oxygen demand.
Want to Apply This Research?
- If monitoring water quality in an aquaculture system, track weekly measurements of ammonia, phosphate, and suspended solids levels. Record the percentage reduction from baseline. Note water temperature, salinity, and oxygen levels to correlate with cleaning efficiency.
- Users managing aquaculture operations could use the app to log which shellfish species they’re using, the environmental conditions they’re maintaining, and the resulting water quality improvements. This creates a personalized record of what works best in their specific situation.
- Set up weekly water quality testing reminders. Track trends over 8-12 weeks to see if shellfish populations are maintaining their cleaning effectiveness. Compare your results against the baseline measurements from this study to gauge your system’s performance relative to laboratory conditions.
This research is laboratory-based and has not been tested in real-world aquaculture or natural water systems. Results may vary significantly depending on environmental conditions, water volume, and other factors. Before implementing any shellfish-based water treatment system, consult with environmental scientists, aquaculture specialists, and local regulatory authorities. This research should not be used as the sole basis for making decisions about water management or species introduction. Some of these shellfish species may be non-native to your region, and introducing them could have unintended ecological consequences. Always follow local environmental regulations and obtain proper permits before using any organisms for water treatment purposes.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.
