Brewer’s Yeast in Tilapia Feed: Replacement Levels for Fish Meal and Soybean Meal

Dried brewer’s yeast works well in tilapia feed at moderate levels. In juvenile Nile tilapia it replaced fish meal at up to 15% of the diet with feed conversion unchanged at 1.5, and in fingerlings it replaced 30% of the soybean meal protein with better growth than the control. Above those levels growth and feed efficiency fall. For most tilapia formulas, yeast is a partner protein that cuts fish meal or soybean meal, not a full replacement for either.

This guide summarises the two most useful tilapia trials, explains why results drop at high inclusion, and sets out how to test yeast in your own feed.

Why tilapia is a good fit for yeast protein

Tilapia are omnivores and already eat diets built mostly on plant protein, so formulators are not trying to replace a large fish meal share as they are in shrimp or salmon feed. The question is narrower: can yeast take out the last few percent of fish meal, or part of the soybean meal, at equal or lower cost per kilogram of fish? Yeast suits that role because it is palatable, low in fibre and free of the anti-nutritional factors found in soybean meal.

Trial 1: replacing fish meal in juvenile Nile tilapia

Ozório and colleagues fed juvenile Nile tilapia (7.6 g starting weight) for 51 days on diets with 0, 10, 15, 20, 30 and 40% dried brewer’s yeast. Fish meal fell from 25% of the diet to zero as yeast rose; at 40% yeast it was fully replaced.

Feed intake did not differ between diets, and protein and lipid digestibility stayed in the same range (78–82% and 87–94%). So the fish ate the yeast diets and digested them; the drop at high levels came from lower protein retention, not from refusal. The authors concluded that dried yeast is palatable and suitable up to 15% inclusion.

Trial 2: replacing soybean meal in fingerlings, in clear water and biofloc

A 2024 study led by Nguyen Huu Yen Nhi fed GIFT-strain Nile tilapia (about 50 g) for 60 days, with spent brewer’s yeast replacing 0, 30, 60 or 100% of the soybean meal protein. Fish were raised in two systems: a biofloc recirculating system and a clear-water recirculating system.

Growth followed a curve that rose to a peak at partial replacement and then fell. The authors put the optimum somewhere between 30 and 60% of soybean meal protein and concluded that mixing the two proteins worked better than relying on either alone. Biofloc fish did better at every level, partly because the floc itself supplied extra protein.

Why performance drops at high inclusion

• Amino acid balance. Yeast is relatively low in methionine. As inclusion rises without rebalancing, methionine becomes limiting and protein retention falls, which matches the lower nitrogen gain seen at 40% in the first trial.
• Nucleic acids. Yeast is rich in RNA. Fish handle moderate amounts well, but very high levels add nitrogen the fish cannot use for growth.
• Cell wall digestibility. Part of the yeast protein sits inside a tough cell wall. Feedipedia notes that disrupting the wall can improve its value for fish, which is one reason hydrolysed yeast products exist.

Practical use levels

These ranges come from trials with specific base formulas, fish sizes and systems. Use them to set your test levels, not as a final recipe.

How to run your own tilapia trial

1. Decide what yeast replaces. Fish meal and soybean meal give different results and different savings. Test one at a time.
2. Formulate on analysed values. Get protein, moisture and the amino acid profile of the yeast you will buy. Feed-grade dried brewer’s yeast is usually 40–46% crude protein.
3. Test three levels against your current feed, for example low, middle and high, keeping everything else equal.
4. Rebalance methionine and lysine at each level.
5. Check pellet quality on your line before the growth trial, especially floating feed expansion and water stability.
6. Measure what pays: weight gain, FCR, survival and feed cost per kilogram of fish.

Related reading: brewer’s yeast for catfish and pangasius feed and brewer’s yeast in sea bass and barramundi feed.

Sources

• Ozório ROA, Portz L, Borghesi R, Cyrino JEP (2012). Effects of dietary yeast (Saccharomyces cerevisiae) supplementation in practical diets of tilapia (Oreochromis niloticus). Animals 2(1): 16–24
• Nhi NHY, Lan TT, Baruah K, Lundh T, Kiessling A (2024). Gradual replacement of soybean meal with brewer’s yeast in fingerling Nile tilapia diet. Aquaculture Journal 4: 255–269
• Feedipedia (INRAE, CIRAD, AFZ and FAO). Brewers yeast