Scientists tested two different types of plant extract from Angelica sinensis (a traditional herb) on young carp fish to see how it affected their growth and body composition. Over six weeks, they fed 780 fish different diets containing either low-strength or high-strength versions of the plant extract. They found that the low-strength extract slowed down fat buildup but helped fish build more muscle, while the high-strength extract did the opposite—it helped fish gain weight and fat faster. These findings could help fish farmers choose better feed ingredients to control how their fish grow.

The Quick Take

  • What they studied: Whether two different strengths of a plant extract (Angelica sinensis) would change how fast fish grow, what their bodies are made of, and how their bodies process food
  • Who participated: 780 juvenile carp fish (a common farm fish) divided into 13 different feeding groups, with each group tested in three separate tanks over 42 days
  • Key finding: The weaker plant extract slowed fish growth and fat storage but increased muscle protein, while the stronger extract did the opposite—it boosted growth and fat buildup along with muscle gain
  • What it means for you: If you’re involved in fish farming, this suggests you could use different plant extracts to control whether your fish grow quickly with more fat or more slowly with more muscle. However, this research is specific to carp and may not apply to other fish species or animals.

The Research Details

Researchers took 780 young carp and randomly divided them into 13 groups. One group ate regular fish food (the control group), six groups ate food mixed with different amounts of low-strength plant extract, and six groups ate food with different amounts of high-strength plant extract. All fish were kept in separate tanks with three copies of each group to make sure results were reliable. The fish were fed these special diets for exactly 42 days (about 6 weeks). Scientists then measured how much the fish grew, what their bodies were made of (muscle versus fat), and how well their bodies processed food by testing their blood and measuring their waste.

By testing both weak and strong versions of the same plant extract, researchers could see if the strength of the extract made a difference. Using many fish (780 total) and repeating each group three times helps make sure the results weren’t just by chance. The 42-day timeframe is long enough to see real changes in how fish grow and develop.

This study has good design features: it used a large number of fish, had a control group for comparison, and repeated each test group three times. However, the study only looked at one type of fish (carp), so results might not apply to other fish species. The research was published in a peer-reviewed journal, which means other experts checked the work before publication.

What the Results Show

The low-strength plant extract had surprising effects: it actually slowed down how fast the fish gained weight and reduced how much fat they stored in their bodies. However, it helped them build more muscle protein. The extract also reduced the activity of digestive enzymes (the proteins that break down food), which explains why the fish absorbed less fat and amino acids from their food. Blood tests showed lower levels of fats and ammonia in fish eating this extract.

The high-strength plant extract did the opposite: it helped fish grow faster and gain more weight, with increases in both fat and muscle. This stronger version boosted the fish’s ability to digest and absorb proteins and fats from their food. The fish’s bodies were more efficient at processing nutrients and building tissue.

Both extracts changed how the fish’s bodies processed different types of nutrients. The low-strength version shifted the fish’s metabolism toward burning more carbohydrates and fats while preserving protein. The high-strength version enhanced the fish’s ability to use all types of nutrients for growth.

Additional measurements showed that the low-strength extract reduced ammonia levels in the fish’s blood and decreased how much ammonia they excreted (released as waste). This suggests the fish were processing protein more efficiently. The high-strength extract increased the activity of enzymes involved in digestion, showing that the fish’s digestive systems became more powerful. Both extracts affected the fish’s condition factor (a measure of how healthy and well-fed they look), with opposite effects matching their growth patterns.

This research adds to growing evidence that plant-based feed additives can fine-tune how animals grow and develop. Previous studies have shown that herbal extracts can affect metabolism in fish and other animals, but this study is unique in comparing two different strengths of the same extract. The findings support the idea that the concentration (strength) of a plant extract matters just as much as which plant is used.

This study only tested one species of fish (carp), so we don’t know if the same results would happen with other fish species or other animals. The research was done in controlled tank conditions, which may not reflect how fish behave in natural environments or large-scale farms. The study didn’t test the long-term effects beyond 42 days, so we don’t know if these changes would continue or reverse over longer periods. Additionally, the study focused only on the plant extract itself and didn’t test whether these effects would work the same way if the extract were combined with other feed ingredients commonly used in fish farming.

The Bottom Line

If you’re a fish farmer raising carp, this research suggests you could use low-strength Angelica sinensis extract if you want to produce leaner fish with more muscle and less fat, or high-strength extract if you want faster-growing fish with more overall weight gain. However, these are preliminary findings based on one study with one fish species. Before making changes to your fish feed, consult with an aquaculture nutritionist and consider testing on a small scale first. The confidence level for these recommendations is moderate—the study was well-designed but limited to one fish type.

Fish farmers and aquaculture businesses raising carp would find this most relevant. Feed manufacturers developing fish food products might also be interested. This research is less relevant to people who eat fish, as the extract would be processed out during cooking. People interested in herbal supplements might find the plant extract interesting, but this study only tested it in fish, not humans.

The changes in fish growth and body composition appeared within the 42-day study period, with measurable differences visible after several weeks. If you were to apply this to fish farming, you’d likely see noticeable changes in your fish within 4-6 weeks of switching feed. However, longer-term effects beyond 6 weeks are unknown.

Want to Apply This Research?

  • If using this research for fish farming, track weekly weight gain, feed conversion ratio (how much food produces how much growth), and visual body composition changes. Measure these metrics for each feeding group to compare performance over 6-week periods.
  • Fish farmers could implement a trial by dividing their carp population into groups fed with different extract strengths, then monitoring growth rates and body composition monthly. Use the app to log feed amounts, fish weights, and health observations to compare results against baseline data.
  • Establish a baseline measurement of your current fish growth rates and body composition. After introducing the plant extract, track the same metrics weekly for at least 6 weeks. Compare results between groups to determine which extract strength best matches your farming goals (lean muscle versus rapid growth). Document any changes in feed efficiency, fish health, or mortality rates.

This research was conducted on carp fish in controlled laboratory conditions and may not apply to other fish species, other animals, or humans. The study was funded and published in a peer-reviewed journal but represents preliminary findings from a single study. If you are a fish farmer considering using Angelica sinensis extract in your feed, consult with an aquaculture veterinarian or nutritionist before making changes. This information is for educational purposes and should not replace professional agricultural or veterinary advice. Always follow local regulations regarding feed additives and aquaculture practices in your region.