Choosing the correct pellet size is just as important as selecting the correct feed formulation. Pellets that are too large may be difficult to consume. Pellets that are too small can increase losses, reduce feeding efficiency and add unnecessary waste. Manufacturers therefore offer a wide range of sizes for species and life stage.
See also
Typical pellet sizes
The table is orientation. Actual size follows species, mouth form and the manufacturer table — do not invent millimetres.
| Fish size | Typical feed form |
|---|---|
| Larvae | Live feed, microdiets (< 0.5 mm) |
| Fry (about 0.1–5 g) | Small starter pellets — manufacturer table |
| Fingerlings (about 5–20 g) | Next step in the manufacturer series |
| Juveniles (about 20–100 g) | Mid size — species and manufacturer |
| Grow-out (about 100–500 g) | Larger pellets — see species notes below |
| Large grow-out (> 500 g) | Largest commercial size for the species |
Not a dosing table. Always use the current feed series.
Species differences
Different species have different feeding behaviour and mouth structure. That influences optimal pellet size as much as body weight.
Salmonids (salmon, trout, Arctic char) typically use larger pellets as they grow. Commercial grow-out diets often sit in the 4–12 mm range; large harvest salmon may receive pellets above 10 mm. Tilapia generally prefer somewhat smaller pellets at a given body weight; common sizes sit in the 1–6 mm range. Sea bass and sea bream often use 1–8 mm depending on size — buoyancy and sinking also matter. Shrimp use specialised sinking feeds that step up as they grow. Always species + manufacturer, not a generic millimetre rule.
Why pellet size matters
Correct sizing can improve intake, growth, FCR, feeding behaviour and water quality. The wrong size can increase losses, reduce growth, raise FCR and produce more sludge and ammonia. In intensive RAS even small increases in wasted feed load drum filters, protein skimmers, biofilters and sludge handling. See FCR, sludge and Ammonia / TAN.
Pellet size changes during production
As fish grow, pellet size is stepped up. An example for trout or salmon (orientation, not a product line): 0.8 mm → 1.5 mm → 2 mm → 3 mm → 4.5 mm → 6 mm → 9 mm → 12 mm. Larger pellets too early reduce growth because smaller fish cannot eat them efficiently. Excessively small pellets to large fish increase losses and feeding time.
Practical rule of thumb
Feed composition determines what the fish eat. Pellet size determines how efficiently they can eat it. A good feed in the wrong size can perform worse than a slightly less advanced feed in the right size. As fish grow, pellet size should grow with them.
Sources/overview (selection): established commercial feed practice for salmonids, tilapia and marine fish; manufacturer size tables. Orientation, not a product or dosing table. Empty millimetre cells in the draft were left unfilled on purpose. See also feed types and feeding systems.