Using AquaGut to Push the Envelope on Feed Conversion

September 25, 2025

One of the quiet triumphs of modern salmon farming has been the steady improvement in feed conversion. Thirty years ago, it took roughly 2 kilograms of feed to produce 1 kilogram of live fish. Today, leading farms often report a ratio close to 1:1. By livestock standards, that’s extraordinary—better than poultry, swine, or cattle.

Other species haven’t benefited from extensive research and targeted research nutritional science applied to Atlantic salmon. Many are still trying to make production economics work with feeds that struggle to meet key nutritional needs and result in high FCRs.

Tuning Nutrition in Real Time

Nutritional needs are impacted by farm conditions, seasons, stressors and a host of other factors. An excellent diet developed in a research facility in mid-Norway or through testing on mink or trout, may not deliver the same result in all regions. With exceptionally long production cycles for most fish, the feed back loop on feed performance, given all of the other macro and micro factors impacting performance is almost non-existent.

In the real world, a salmon spends a big share of feed energy just staying alive (respiration/maintenance), and another chunk leaves as feces—even on good days. Farm-scale budgets put it roughly at: ~48% maintenance, ~19% fecal loss, ~30% growth. That last slice is the only one we get paid for. Given the relative lack of research on diets for other species, the situation is worse for kingfish, barramundi, king salmon etc.

That’s why “just use better ingredients” rarely delivers the miracle. You can raise apparent digestibility coefficients, but you still have:

• Maintenance burn that never goes to zero,

• Endogenous losses (sloughed cells, mucus) that cap “apparent” digestibility below 100%, and

• Limiting AAs/energy balance issues that turn surplus protein into nitrogen waste instead of growth.

• A potential multi-year wait before you get any meaningful feedback

AquaGut - A Critical Tool for On-farm Feedback

The fix isn’t pretending biology is tidy. It’s shortening the feedback loop so we can keep the gut in the “green zone” and stop the controllable losses from swelling.

A farmer told me last week they couldn’t collect a fecal sample from kingfish in the water column —the feces just turned into a cloud. That’s not a sampling problem (it can be overcome with another collection method); it’s a performance problem. Cloudy feces = nutrients paid for but not used. When chronic enteritis shows up, the fecal slice grows and maintenance costs rise (immune activation isn’t free). You feel it weeks later as a drift in FCR and growth.

Sample AquaGut Biome Testing Results

This is where AquaGut earns its keep. Early, species-specific gut readouts let nutritionists:

• catch inflammation before FCR drifts,

• tune ingredients/additives to lift the limiting digestibility (the bottleneck that really reduces feed) in real-time, and

• hold the line on gut integrity so the “unused feed” slice stays small.

You won’t break physics. But you can provide immediate feedback to your feed supplier and turn waste back into weight. Even moving crude-protein ADC from ~86% toward ~95% trims on the order of ~10% feed to meet the same digestible-protein target—before counting knock-on gains from calmer guts and steadier intake.

As a consultant, I don't have direct accountability for farms or fish these days but I'm convinced AquaGut is how you make the math win more often. If your company is interested in a commercial trial, let me know.