Striped catfish from nursery to grow-out: probiotics, digestive enzymes and feed protein and fat in new research

In short: no 2025–2026 study has followed striped catfish all the way from nursery to grow-out, so this article combines the latest research for each stage. In the nursery stage, a trial published on 30 October 2026 shows that adding a probiotic to feed already containing a digestive enzyme made fingerlings grow faster with a lower FCR, but higher doses did no better. Two other studies show probiotics helped fingerlings survive the nursery phase and a bacterial challenge. In grow-out, 28% protein feed gave a better FCR than 32%, while high-fat feed built up belly fat and enlarged the liver.

Nursery stage: probiotic plus digestive enzyme

The paper appeared in Animals on 30 October 2026, from the University of the Punjab and the University of Veterinary and Animal Sciences, Lahore (Pakistan), with the University of Aberdeen (UK) and the University of Galway (Ireland). The authors report no external funding and no conflicts of interest.

• Fish and tanks: 600 fingerlings of 10.17 g, 30 glass aquaria of 100 litres (20 fish each, 3 aquaria per diet), fresh water at 24–28 °C, one third of the water changed daily, 90 days.
• Feed: 10 diets, all 35% protein, mostly plant protein (sunflower, soybean and canola meals; 10% fishmeal). Fed twice a day at about 3% of body weight.
• Additives: a commercial protease (a protein-digesting enzyme) at 0.5 or 1.0 g/kg feed, combined with a commercial probiotic at 0, 1, 2, 3 or 4 g/kg. The probiotic contained Bacillus licheniformis and B. subtilis (5 × 10⁹ CFU/g each) and Enterococcus faecalis (5 × 10⁸ CFU/g). Additives were mixed into the ingredients before pelleting.

• With protease 0.5 g/kg: adding 2 g/kg probiotic gave fish of 60.8 g versus 52.3 g, and FCR 1.33 versus 1.60. Going to 3–4 g/kg added nothing.
• With protease 1.0 g/kg: 1–2 g/kg probiotic was best (FCR 1.37–1.38); 4 g/kg did worse (FCR 1.57, 53.4 g fish).
• The authors’ calculated optimum probiotic dose: about 1.4–1.7 g/kg of feed.
• Feed intake was almost the same in every group, so the extra growth came from better digestion and feed use.
• Inside the fish: gut digestive enzymes rose, liver antioxidant enzymes rose and MDA (a marker of oxidative damage) fell; blood lysozyme and IgM antibody rose; flesh composition did not change.

Probiotics and catfish survival

The Pakistan trial could not measure survival because no fish died. Two other studies have these data:

• Bangladesh (2021), the only study following fish from larvae to grow-out: a commercial probiotic at 0.2 g/kg feed, three times a day, given only in the two nursery phases in net pens in a pond. Larvae to fry (20 days, 400 fish/m³): 40.27% survival versus 30.05%. Fry to fingerlings (45 days, 200 fish/m³): fish given probiotics in both phases survived at 58.58%, fish never given probiotics at 28.73%. Grow-out for 90 days in concrete tanks (12 fish/m³, no probiotic for any group): 97% versus 83%, not statistically significant.
• Thailand (2025, Kasetsart University): 37 g catfish in 16 tanks of 200 litres × 15 fish, fed for 30 days with a Bacillus subtilis strain (about 10¹² CFU/kg feed according to the paper), its cell-free postbiotic, or both. The fish were then injected with Edwardsiella tarda at 10⁷ CFU per fish and followed for 14 days: survival 87.5% (both), 84.37% (postbiotic), 81.25% (probiotic) versus 62.5% for controls. One author works for a feed company; the paper states the company had no role in design or analysis.

Grow-out stage: enough protein, not too much fat

A study in Scientific Reports (30 September 2025) from the ICAR-Central Institute of Fisheries Education and partner institutes in India:

• Design: 168 g catfish in 27 net pens of 2 × 3 × 1.5 m inside one 1.1 ha earthen pond, 1.6 m deep, at 10 fish/m³, 3 pens per diet, 8 weeks, water at 27–30.5 °C. Floating 3 mm pellets fed to satiation twice a day.
• Diets: 9 formulations combining 28, 30 or 32% protein with 4, 6 or 8% lipid.

• 32% protein did worst: average FCR 2.41 and 283 g fish, versus FCR 1.92 and 308 g at 28% protein.
• High fat builds fat: lipid level on its own did not change growth, but the more fat in the feed, the more belly fat (0.27% → 0.43% → 1.33%) and the larger the liver (liver index 2.41 → 2.52 → 2.65%).
• 28% protein, 4% lipid: FCR 1.81, the least belly fat, the smallest liver, good water-holding flesh and the least rancidity; 313 g fish, on a par with four other good diets.

In practice: what catfish farmers can take from this

• The nursery stage is where probiotics have the clearest data. In Bangladesh, survival from larvae to fingerlings doubled when probiotics were fed continuously through both nursery phases (58.6% versus 28.7%).
• Trial doses: in Pakistan, the optimum of 1.4–1.7 g/kg of a product at about 10¹⁰ CFU/g equals roughly 1.5–1.8 × 10¹⁰ CFU per kg of feed (illustrative calculation by Than Vuong). Products differ in strength, so follow the label of the product you use.
• More is not better. With a digestive enzyme already in the feed, too much probiotic made results worse.
• Mixing: in the trial, additives went into the ingredients before pelleting. On farms they are usually coated onto pellets, so mix evenly, coat and let dry so the product does not wash off in water.
• Grow-out: higher-protein feed is not necessarily better, and high-fat feed makes fish fatter with larger livers. Track FCR at each fish weighing and check livers when sampling fish.
• Context: these studies were done in Pakistan, Thailand, Bangladesh and India, in fresh water, in tanks or net pens, over short periods. They do not include data from commercial catfish ponds in the Mekong Delta.

Quick questions

Sources

1. Tanveer A., Khan N., Fatima M., Shakir H.A., Ali W., Khizar A., Martin S.A.M., Davies S.J. Effects of Dietary Protease at Different Levels of Probiotics on the Growth Potential, Enzyme Activities, Physiological and Hematoimmune Responses of Striped Catfish (Pangasianodon hypophthalmus). Animals 2026;16(21):3431 DOI 10.3390/ani16213431. Open access, CC BY.
2. Haque M.M., Hasan N.A., Eltholth M.M., Saha P., Mely S.S., Rahman T., Murray F.J. Assessing the impacts of in-feed probiotic on the growth performance and health condition of pangasius (Pangasianodon hypophthalmus) in a farm trial. Aquac Rep 2021;20:100699 DOI 10.1016/j.aqrep.2021.100699. Open access, CC BY.
3. Wiratama N., Meachasompop P., Kumwan B. et al. Dietary Probiotic Bacillus subtilis AAHM-BS2360 and Its Postbiotic Metabolites Enhance Growth, Immunity, and Resistance to Edwardsiellosis in Pangasianodon hypophthalmus. Antioxidants 2025;14(6):629 DOI 10.3390/antiox14060629. Open access, CC BY.
4. Prakash P., Mohanta K.N., Sahu N.P., Renuka V., Varghese T., Nayak S.K., Baraiya R., Khalasi Y. Optimizing dietary protein and lipid levels for better growth performance, nutrient retention and flesh quality of grow-out striped catfish (Pangasianodon hypophthalmus). Sci Rep 2025;15:33874 DOI 10.1038/s41598-025-07933-3. Open access, CC BY-NC-ND.

This article is a synthesis and interpretation by Than Vuong. Numbers come from the full text of the original papers; charts were redrawn by Than Vuong and the papers’ own figures and tables are not reproduced. Trade names of the products used in the studies are omitted. The "In practice" section is editorial opinion.