Scientists tested whether adding a special type of seaweed called Sargassum polycystum to fish food could help young red tilapia grow better. They tried three different ways to dry the seaweed and then fed it to fish for 49 days. Fish that ate food with 3% seaweed powder grew better, survived longer, and ate their food more efficiently than fish on regular diets. The seaweed-fed fish also had slightly different blood chemistry, but nothing harmful. This research suggests that seaweed could be a natural, healthy ingredient in fish farming that helps produce better quality fish for food.

The Quick Take

  • What they studied: Whether adding freeze-dried seaweed powder to fish food helps young red tilapia grow faster and healthier
  • Who participated: Young red tilapia fingerlings (small fish) divided into groups eating different diets, with one group eating regular food and others eating food mixed with different amounts of seaweed powder
  • Key finding: Fish eating food with 3% seaweed powder had better survival rates, ate more food, and converted that food into body growth more efficiently compared to fish on regular diets
  • What it means for you: If you eat farmed tilapia, this research suggests farmers could use seaweed as a natural ingredient to produce healthier, better-quality fish. This may lead to more nutritious fish at your grocery store, though more research in larger operations is needed to confirm benefits

The Research Details

Researchers first tested three different ways to dry seaweed—air-drying at room temperature, freeze-drying, and vacuum oven drying—to see which method preserved the most nutrients. They used special laboratory techniques to measure the chemical differences between the dried seaweeds. After choosing the best drying method, they created fish food with different amounts of seaweed powder and fed it to young tilapia fish for 49 days (about 7 weeks). They measured how much the fish grew, how much food they ate, how well they survived, and checked their blood to see if the seaweed affected their health.

This approach is important because it shows how to properly prepare seaweed to keep its nutrients, and then tests whether those nutrients actually help fish grow better in real feeding situations. Understanding the best way to use seaweed in fish farming could help farmers produce healthier fish more sustainably, since seaweed is a natural, renewable resource that doesn’t require the same resources as traditional fish feed ingredients

The study was published in Scientific Reports, a well-respected scientific journal. The researchers used proper laboratory methods to analyze the seaweed and conducted a controlled feeding trial where different groups of fish received different diets. However, the exact number of fish used in the study wasn’t clearly stated in the abstract, and the study lasted only 7 weeks, so longer-term effects aren’t known. The results show statistical significance (p < 0.05), meaning the differences found are unlikely to be due to chance

What the Results Show

Fish that ate food containing 3% seaweed powder showed the best results overall. These fish had higher survival rates (more fish stayed alive), consumed more food, and were more efficient at converting the food they ate into body growth compared to the control group eating regular food. The freeze-dried seaweed method preserved nutrients better than the other drying methods tested. When researchers looked at the fish’s body composition, they found no significant differences in fat content, protein content, or the types of fats between the seaweed-fed fish and control fish, suggesting the seaweed didn’t change what the fish were made of—just helped them grow more efficiently.

Blood tests showed that fish eating seaweed-enriched diets had slightly higher levels of certain substances in their blood, including liver enzymes, digestive enzymes, calcium, cholesterol, total protein, and triglycerides. These increases were small and the researchers noted they weren’t concerning, but they do show that the seaweed was being absorbed and processed by the fish’s body. These changes suggest the seaweed was being digested and used by the fish, rather than just passing through their system

This research builds on previous studies showing that seaweed can be beneficial in fish diets. The finding that 3% seaweed is an effective amount aligns with other research on seaweed supplementation in aquaculture. The study adds to growing evidence that natural plant-based supplements like seaweed could replace some traditional fish feed ingredients, which is important as the aquaculture industry looks for more sustainable and environmentally friendly feeding options

The study only lasted 7 weeks, so we don’t know if the benefits continue over longer periods or through the fish’s entire life. The exact number of fish used wasn’t specified in the available information. The research was done in controlled laboratory conditions, so results might differ in large-scale commercial fish farms with different water conditions or management practices. Only one species of fish (red tilapia) was tested, so we don’t know if the same benefits would apply to other farmed fish species. The study didn’t compare seaweed to other natural supplements, so we can’t say whether seaweed is better or worse than other options

The Bottom Line

Based on this research, fish farmers may want to consider adding 3% freeze-dried Sargassum polycystum powder to tilapia feed as a way to improve growth and survival rates. This recommendation has moderate confidence because the study showed clear benefits, but larger-scale farm trials would strengthen the evidence. Consumers interested in sustainable seafood may find this development encouraging, as it represents a move toward more natural, plant-based fish farming practices

Fish farmers and aquaculture companies should care about this research, as it offers a practical way to improve fish growth and reduce feed waste. Seafood consumers interested in sustainability and nutrition should care, as it could lead to healthier, more sustainably-produced fish. Environmental advocates should care because using seaweed reduces reliance on other feed ingredients that may have larger environmental impacts. People with fish allergies or those avoiding seafood don’t need to apply these findings

Based on this 7-week study, improvements in fish growth and survival would likely be visible within 4-8 weeks of adding seaweed to the diet. However, longer-term benefits and any effects on fish quality at market size (larger fish) would take several months to evaluate. If this approach is adopted by farms, consumers might see benefits in fish quality within 6-12 months as farms transition to the new feeding practice

Want to Apply This Research?

  • If you’re a fish farmer using this research, track weekly fish weight gain, feed consumption amounts, and survival rates for groups eating seaweed-supplemented feed versus regular feed. Compare the feed conversion ratio (how much feed is needed to produce one pound of fish growth) between groups
  • Fish farmers could implement a gradual transition by starting with 1-2% seaweed powder in feed, monitoring fish health and growth for 2-3 weeks, then increasing to the recommended 3% level. This allows observation of any changes in fish behavior or health before full implementation
  • Establish a baseline of current growth rates and feed efficiency, then monitor weekly for the first month after introducing seaweed supplementation. Track survival rates, average fish weight, feed consumption, and any visible health changes. Continue monthly monitoring for at least 3 months to confirm sustained benefits and identify any long-term effects

This research describes results from a controlled laboratory study on young tilapia fish and should not be considered medical advice for humans. While the study suggests seaweed supplementation is safe for fish based on blood chemistry results, individual results may vary in different farming conditions. Fish farmers should consult with aquaculture specialists before making major changes to feeding programs. Consumers should note that this research is about fish farming practices and does not directly address human health benefits from eating seaweed-supplemented fish. Always consult healthcare providers for personal nutrition decisions.