Researchers tested whether a fermented plant called Astragalus membranaceus could help common carp fish grow better and stay healthier. They fed different groups of fish regular food or food mixed with this plant that had been processed with helpful bacteria. After 8 weeks, the fish that ate the plant-supplemented food grew significantly larger, gained weight faster, and had better immune systems than the control group. The fermented plant appeared to reduce harmful stress in the fish’s bodies and boost their natural defenses, suggesting this supplement could be valuable for fish farming.

The Quick Take

  • What they studied: Whether feeding fish a supplement made from fermented Astragalus membranaceus (a traditional plant) mixed with helpful bacteria would improve their growth, health, and immune system
  • Who participated: 225 common carp fish (a type of freshwater fish used in farming) weighing about 44-45 grams each, divided into 5 groups of 45 fish each, studied over 8 weeks
  • Key finding: Fish fed the fermented plant supplement grew significantly larger and faster than control fish, with some groups showing 15-20% better growth rates and improved immune function markers
  • What it means for you: If you’re involved in fish farming, this suggests fermented plant supplements could improve fish health and profits. For consumers, healthier farmed fish may mean better quality food. However, more research is needed before widespread use in commercial farming.

The Research Details

Scientists divided 225 young common carp into five equal groups of 45 fish each. One group (the control) received only regular fish food. The other four groups received the same regular food but with added fermented Astragalus membranaceus that had been processed with different types of helpful bacteria: Lactobacillus plantarum, Saccharomyces cerevisiae, Bacillus subtilis, or a combination of all three. All fish were fed this way for 8 weeks while researchers measured their growth, weight gain, food efficiency, and immune system markers.

The researchers chose fermentation because it’s a process that breaks down the plant material, making it easier for fish to absorb and use the beneficial compounds. This is similar to how fermenting vegetables makes them easier for humans to digest. They measured multiple health indicators including how much the fish grew, how efficiently they converted food into body weight, and various markers of immune and antioxidant function in their blood and intestines.

This type of controlled experiment allows researchers to see direct cause-and-effect relationships between the supplement and fish health, since all other conditions (water quality, temperature, light, regular food) were kept the same across all groups.

This research matters because oxidative stress (a type of cellular damage) is a major problem in fish farming that slows growth and reduces profits. Finding natural supplements that reduce this stress could help farmers produce healthier fish more efficiently without relying on antibiotics or synthetic chemicals. The fermentation process is important because it makes the plant’s beneficial compounds more available for the fish to use.

This study has several strengths: it used a reasonable sample size (225 fish), included multiple treatment groups to compare, used three replicate tanks per group to ensure results weren’t due to chance, and measured multiple health outcomes. The study was published in a reputable peer-reviewed journal (Frontiers in Immunology). However, the study was conducted only in laboratory conditions with one fish species, so results may not apply to all fish or to wild populations. The researchers don’t mention whether they were blinded to which group was which, which could introduce bias.

What the Results Show

Fish that received the fermented plant supplement grew significantly larger than control fish. Specifically, fish fed the supplement had higher final body weight, faster weight gain rates, and better feed efficiency (meaning they converted their food into body weight more effectively). The feed conversion ratio—a measure of how much food is needed to produce one unit of body weight—was notably lower in supplemented groups, meaning these fish needed less food to grow the same amount.

The supplement also boosted the fish’s natural antioxidant defenses. Antioxidants are like the body’s cleanup crew, removing harmful molecules called free radicals that damage cells. Fish fed the fermented supplement had higher levels of antioxidant enzymes in their blood and tissues, suggesting their bodies were better protected from cellular damage.

Perhaps most importantly, the supplement improved immune function. The fish’s intestines—which are crucial for both nutrition and immunity—showed better barrier function, meaning they were better at keeping harmful bacteria out while absorbing nutrients. The supplement also reduced inflammation markers in the fish’s bodies, suggesting it calmed down excessive immune responses that can be harmful.

All four fermented preparations (single bacteria types and the combination) showed benefits, though the combination appeared to work slightly better than individual bacteria strains in some measures.

The research found that the fermented supplement inhibited a specific immune pathway called TLR4/MyD88/NF-κB, which is responsible for triggering inflammatory responses. By calming this pathway, the supplement reduced pro-inflammatory molecules in the fish’s bodies. This is significant because while some inflammation is necessary for fighting infection, excessive inflammation damages healthy tissue and slows growth. The supplement appeared to strike a better balance. Additionally, the intestinal barrier improvements suggest the fish could absorb nutrients more effectively and resist intestinal infections better.

Astragalus membranaceus has been used in traditional medicine for centuries and previous research has shown it has antioxidant and immune-boosting properties. However, one major limitation has been that the plant’s beneficial compounds don’t absorb well in the body—a problem called low bioavailability. This study builds on prior work by showing that fermentation (processing with helpful bacteria) significantly improves how well these compounds work. This finding aligns with other research showing that fermentation can enhance the effectiveness of plant-based supplements. The results in fish are promising and suggest similar benefits might occur in other animals, though this hasn’t been tested yet.

This study was conducted only in laboratory conditions with one fish species (common carp), so results may not apply to other fish species or to fish in natural environments. The study didn’t test different doses of the supplement, so we don’t know if more or less would work better. The researchers didn’t follow the fish after the 8-week study ended, so we don’t know if benefits persist long-term. The study also didn’t compare the fermented supplement to other known growth-promoting supplements, so we can’t say if this is better than existing options. Finally, while the study measured many health markers, it didn’t measure actual disease resistance by exposing fish to pathogens.

The Bottom Line

For fish farmers: Consider testing fermented Astragalus membranaceus supplements in small-scale trials before large-scale implementation. The evidence suggests potential benefits for growth and health, but more research in commercial farming settings is needed. (Confidence: Moderate - promising results in controlled settings, but limited real-world testing)

For consumers: This research doesn’t directly affect food choices yet, as these supplements aren’t widely used in commercial fish farming. However, it suggests that natural, fermented supplements could eventually improve farmed fish quality. (Confidence: Low - research is preliminary)

For researchers: This work suggests fermented plant supplements warrant further investigation in aquaculture and possibly other animal agriculture contexts.

Fish farmers and aquaculture companies should pay attention to this research as a potential way to improve profitability and fish health. Feed manufacturers might consider developing fermented supplement products. Researchers studying animal nutrition and natural supplements should find this relevant. General consumers may eventually benefit if these supplements become standard in fish farming, leading to healthier farmed fish. People interested in natural alternatives to antibiotics in animal agriculture should find this encouraging.

In this study, benefits appeared within 8 weeks of feeding the supplement. If a fish farmer were to implement this, they would likely see growth improvements within 4-6 weeks, with maximum benefits by 8-12 weeks. However, real-world results may vary depending on water quality, temperature, fish genetics, and other factors.

Want to Apply This Research?

  • If using this supplement in aquaculture: Track weekly weight measurements of sample fish, feed conversion ratio (amount of feed per unit of weight gain), and visual health indicators (fin condition, coloration, activity level). Record these in a simple spreadsheet or app to monitor trends over 8-12 weeks.
  • For fish farmers: Implement a trial period where 10-20% of your stock receives the fermented supplement while maintaining control groups on regular feed. Monitor growth and health metrics weekly. If results match this study, gradually expand to larger populations while tracking costs versus benefits.
  • Establish baseline measurements before starting supplementation (average fish weight, feed consumption, visible health issues). Then measure the same metrics weekly or bi-weekly for at least 12 weeks. Compare supplemented groups to control groups using simple calculations like average weight gain per week and feed conversion ratio. Keep detailed records of water quality, temperature, and any health issues, as these factors affect results.

This research was conducted on common carp fish in controlled laboratory settings and may not apply to other fish species, wild populations, or commercial farming environments. The study does not constitute medical or veterinary advice. Anyone considering using fermented Astragalus membranaceus supplements in fish farming should consult with an aquaculture veterinarian or specialist, as results may vary based on water conditions, fish genetics, and other environmental factors. This supplement has not been approved by regulatory agencies for use in food-producing animals in most countries, and legal status varies by location. Always follow local regulations regarding feed additives and supplements for farmed fish.