Scientists studied how young striped murrel fish (a popular food fish in India) develop the ability to digest carbohydrates as they grow. By tracking special digestive proteins called enzymes and growth hormones over 35 days, researchers found that babies can start using carbs for energy very early on. This discovery could help fish farmers create cheaper, better food for young fish, which would reduce the high death rates currently seen in fish farms and make fish farming more profitable and sustainable.

The Quick Take

  • What they studied: Whether young striped murrel fish can digest carbohydrates (a type of food energy) and how their bodies change as they grow from hatching to 35 days old
  • Who participated: Striped murrel fish larvae (babies) raised in controlled conditions from the moment they hatched until they were 35 days old. The study tracked their growth, survival, and how their digestive system developed
  • Key finding: Baby fish can digest carbohydrates starting very early in life, with their carb-digesting ability peaking around 7 days after hatching. This means young fish can use carbs as an energy source much sooner than previously thought
  • What it means for you: If you’re involved in fish farming or aquaculture, this suggests you could potentially use more affordable carbohydrate-based feeds for young fish without harming their growth. However, this research is specific to one fish species and would need testing in real farm conditions before making major feed changes

The Research Details

Researchers collected baby striped murrel fish immediately after hatching and studied them over 35 days. They examined the fish at different time points (3, 7, 9, 14, 21, 28, and 35 days old) to see how their bodies changed. The scientists looked at two main things: (1) the amount and activity of a digestive enzyme called pancreatic α-amylase, which breaks down carbohydrates, and (2) growth-related hormones that control how fast the fish grow. They measured these by extracting genetic material from the fish and analyzing protein levels in their pancreas (the organ that makes digestive enzymes).

Understanding when young fish can digest different foods is crucial for creating appropriate diets. If farmers feed young fish foods they can’t digest yet, the fish waste energy and nutrients, grow poorly, and often die. By identifying exactly when digestive capacity develops, scientists can help farmers time their feeding strategies perfectly, reducing waste and improving survival rates

This study was published in Scientific Reports, a reputable peer-reviewed journal. The researchers used established molecular biology techniques to measure enzyme activity and gene expression. However, the study doesn’t specify exact sample sizes, which makes it harder to assess statistical power. The findings are based on laboratory conditions, which may not perfectly reflect what happens in actual fish farms with different water conditions and feeding practices

What the Results Show

The key discovery was that baby striped murrel fish showed a clear pattern in their ability to digest carbohydrates. The digestive enzyme (α-amylase) that breaks down carbs increased significantly between days 3 and 9 after hatching, peaked at day 7, then gradually decreased through day 35. This suggests that young fish have their strongest carb-digesting ability during the first week of life. The researchers also found that growth-related hormones (GH, IGF-I, and IGFBP) were active from the moment the fish hatched and changed throughout development, indicating that growth processes begin immediately. Over the 35-day study period, the fish grew at a rate of 6.39% per day in length, though only 44% of the fish survived to the end of the experiment.

The study identified that the genetic sequence for the carb-digesting enzyme in striped murrel was 85% similar to the same enzyme in a related fish species (Channa argus), suggesting these fish have evolved similar digestive systems. The dynamic expression of growth hormones throughout development indicates that fish growth is controlled by multiple factors that change as the fish matures. The relatively low survival rate (44%) highlights why understanding larval nutrition is so important—better feeding strategies could potentially improve these numbers

This research builds on previous knowledge that fish develop digestive abilities gradually as they grow. The specific finding that striped murrel can digest carbs very early (starting by day 3) is particularly useful because many fish species have been thought to need primarily protein-based diets when young. This study suggests that cost-effective carbohydrate-based feeds might work better for this species than previously assumed, which could be a significant advantage for fish farmers

The study was conducted in controlled laboratory conditions, which may not reflect real fish farm environments with varying water quality, temperature, and feeding competition. The exact number of fish studied wasn’t clearly specified, making it difficult to assess how reliable the results are. The research only followed fish for 35 days, so it’s unclear if these digestive patterns continue as fish grow larger. Additionally, the study measured enzyme activity in the lab but didn’t test whether fish actually grew better when fed carbohydrate-based diets in practice

The Bottom Line

Based on this research (moderate confidence): Fish farmers raising striped murrel could consider incorporating more carbohydrates into feeds for larvae aged 3-14 days, when carb-digesting ability is highest. However, before making major feed changes, conduct small-scale tests on your farm to confirm these results work in your specific conditions. The high mortality rate (56%) suggests that improving larval nutrition through better feed formulation could be very beneficial

Fish farmers and aquaculture businesses raising striped murrel will find this most relevant. Feed manufacturers developing products for this species should pay attention. Researchers studying fish nutrition and development will also find value in these results. This research is less relevant to people who simply eat fish or keep fish as pets, though it could eventually lead to more affordable and sustainable fish farming

If fish farmers implement carbohydrate-based feeds based on these findings, they should expect to see measurable differences in growth rates and survival within the first 35 days of larval rearing. However, it may take several production cycles (months to a year) to fully optimize feeding strategies and see consistent improvements in farm profitability

Want to Apply This Research?

  • If you’re managing a fish farm, track daily survival rate and average fish length at days 7, 14, 21, and 35 post-hatching. Compare these metrics between batches fed different carbohydrate levels to identify the optimal diet composition for your conditions
  • Implement a feeding trial: gradually increase carbohydrate content in larval feed during days 3-14 (when digestive capacity is highest) while monitoring growth and survival. Record feed costs and fish survival rates to calculate return on investment
  • Establish a baseline by tracking current survival and growth rates for 2-3 production cycles. Then implement carbohydrate-adjusted feeds and monitor the same metrics for another 2-3 cycles. Use the app to log daily observations, feed changes, and outcomes to identify patterns and optimize your feeding strategy over time

This research is specific to striped murrel fish larvae and should not be applied to other fish species without additional research. The study was conducted in controlled laboratory settings and results may differ in commercial farm environments. Before making significant changes to fish feed or farming practices, consult with aquaculture specialists and conduct small-scale trials on your farm. This information is for educational purposes and does not replace professional aquaculture advice. Results from laboratory studies do not guarantee identical outcomes in commercial production settings.