Supporting fish immunity requires the right active ingredient, the right dose, and the right timing for each growth stage. When choosing a supplementation program, farmers need to weigh technical evidence, pond conditions, and economic return together.
When weather turns unstable or a fish population shows reduced feeding, farmers often want to step up health-support products. But before raising the dose, three questions need answers: what active ingredient is the product actually supplying, how much of it is the fish population really receiving, and which outcome will be used to judge effectiveness?
A new study in tilapia offers additional grounds for thinking through this question.
1. The TP4 Study: Benefits Don't Scale Proportionally with Dose
A study published in Frontiers in Physiology on September 11, 2026 tested the peptide TP4 in juvenile tilapia feed, with fish starting at an average weight of about 11.67 g. The trial ran for 60 days across four supplementation levels: 0, 2, 4, and 8 g/kg of feed.
At 2 g/kg, fish showed a higher specific growth rate, a lower feed conversion ratio, and improved immune markers compared with the control. This group also showed better protection when challenged with Streptococcus agalactiae.
At 8 g/kg, the antioxidant and immune benefits seen at the lower level were no longer sustained.
The results show that the response to TP4 was dose-dependent under the trial conditions. This is not a dosing recommendation for other commercial products or for Pangasius. Read the original TP4 study.
2. Do Better Immune Markers Mean Fewer Sick Fish?
When reading technical literature, it helps to distinguish three types of results:
Biological markers: enzyme activity, cellular responses, or other indicators linked to immunity.
Resistance in challenge trials: outcomes after fish are exposed to a pathogen under controlled conditions.
Real-world pond performance: growth, survival, cost, and yield under actual production conditions.
These result types complement each other, but none can fully substitute for the others.
A 2015 study on Pangasius (Pangasianodon hypophthalmus) found that β-glucan supplementation could improve certain immune responses. However, after a challenge with Edwardsiella ictaluri, the study found no statistically significant difference in mortality between diet groups.
This illustrates why an "improved immune marker" result should not be turned into a claim of "guaranteed lower disease or mortality." β-glucan study in Pangasius.
3. Correct Dosing Starts with Understanding the Product
When comparing two immune-support products, do not just look at the grams used per kilogram of feed. Check the following:
The name and concentration of the active ingredient.
The species and growth stage the product is labeled for.
The dosing unit: per feed weight, per biomass, or another basis.
Mixing method, duration of use, and storage conditions.
Documentation confirming the actual product formulation.
The same amount of product does not necessarily deliver the same amount of active ingredient.
An illustrative calculation: 2 g of a product containing 10% active ingredient supplies 0.2 g of active ingredient; 2 g of a product containing 20% supplies 0.4 g. This is only a concentration calculation — it does not prove that two products are equivalent in effect or interchangeable.
So do not carry a dose over from a research paper to a product you are currently using just because the ingredient names sound similar.
4. Fish Eating Less: Check Both the Environment and the Ration
FAO notes that feed management needs to match temperature, dissolved oxygen, metabolic waste, stocking density, and the health of the fish population. These factors need to be considered together when adjusting a feeding regime. FAO document on farm feed management.
For products mixed into feed, farmers also need to distinguish between the amount mixed in and the amount the fish actually consume.
For example, if the same inclusion rate is maintained but feed intake drops by half, the total amount of product the fish receive through feed also drops proportionally, assuming the feed is evenly mixed and nothing is lost.
This calculation helps identify the problem, but it does not mean automatically doubling the concentration to compensate. First check actual feed intake, leftover feed, water conditions, and how the fish population is behaving, then discuss the right adjustment with a technical advisor.
5. "The Right Stage" Needs to Be Clearly Defined
A supplementation program should have a clear objective, a start point, and an evaluation point. Before applying one, farmers should prepare the following information:
Fish population: species, size, days of culture, estimated biomass.
Current condition: feeding behavior, activity, mortality, and any abnormal signs.
Pond conditions: water parameters being monitored, recent fluctuations.
Current program: product name, label dose, start date, method of use.
Evaluation goal: feed intake, growth, feed efficiency, or cost.
When proposing a program for a period before transport, a diet change, or adverse weather, ask for guidance specific to the product and the species being farmed. Do not assume one schedule fits every pond.
If the fish population already shows signs of disease or unusual mortality, identify the cause first; adding more support products is not a substitute for professional diagnosis.
6. Judge by Results and Cost, Not Just by the Amount Used
To track a supplementation program, keep consistent records of:
Actual feed used each day.
The amount of supplement used and its corresponding cost.
Fish weight at each sampling.
Fish mortality.
Any concurrent changes in environment, feed, or management practices.
You can calculate:
Supplement cost per kilogram of weight gain = Total supplement cost ÷ Weight gain over the period.
This figure helps track cost, but it does not by itself prove the product's effectiveness. If feed, oxygen, or stocking density are adjusted at the same time, growth results can be influenced by multiple factors.
Where possible, limit changing several factors at once, and keep a full record of any changes that are unavoidable.
7. A Note for Pangasius Farmers
For Pangasius farmers, the TP4 study in tilapia is a useful example for questioning the relationship between dose and effect — not a direct recommendation. Any decision to use a product should still be based on that product's own instructions and on evidence relevant to Pangasius.
When getting advice, ask specifically: which species and size was tested, for how long, and measured by which criteria? These questions help you choose a program with a solid basis and avoid expectations that go beyond the available data.
Thần Vương Cá partners with farmers in choosing the right product, using it correctly, and tracking real-world results. Farmers are welcome to share details about their fish population, feed intake, pond conditions, and current products so we can discuss a suitable care plan together.
