Where Do Programs Break When Reducing Pathogens in Fishmeal?

If you’re trying to reduce pathogens in fishmeal, it helps to start with a blunt reality. Fishmeal (and the dust and equipment around it) behaves like a low-moisture system. Pathogens often won’t grow in it, but they can survive and move through a facility—especially when dust, condensation and recontamination aren’t tightly controlled. That’s why the strongest programs treat pathogen reduction as a chain of controls, not a single “kill step.”

Below is a practical, technical way to think about it.

1) Don’t Overfocus on Fishmeal and Miss the Environment

In fish feed systems, Salmonella has been documented in ingredients, finished feed and factory environments, with ingredient introduction and environmental persistence often discussed together.

Salmonella has also been evaluated for its ability to form biofilms. That matters because biofilms can help organisms persist through dry periods and routine cleaning. If your facility has “resident” niches—coolers, conveyors, bucket elevators, dust ledges—those sites can keep reseeding product streams even after you think you’ve corrected a one-off event.

2) Validate Lethality With Low-Aw Thinking

Thermal processing is a cornerstone, but low water activity can reduce how quickly microbes are inactivated by heat compared with wetter systems. That concept is well recognized in low-aw food safety literature and is directly relevant to dry meals and dusty environments.

A useful next step is to look beyond temperature alone and consider:

• What was the moisture/aw in the material at that moment?

• Did the process deliver uniform residence time, or was there short-circuiting?

• Are you validating with your matrix (or at least a close proxy), rather than relying on generic assumptions?

3) Extrusion Helps, but It Isn’t Magic

Aquafeed extrusion and related production technologies can contribute to microbial control when they deliver the right time–temperature–moisture–mechanical energy package. But the key word is when. Equipment type doesn’t guarantee outcome; settings and verification do.

4) Invest in the Post-Heat Zone, Where Most Failures Happen

Many mills win the heat step and lose control afterward. Post-process areas are where dust, condensation and traffic flow can quietly reintroduce contamination. Feed biosecurity guidance often emphasizes zoning, movement control and hygiene routines across the whole chain for exactly this reason.

A simple way to pressure-test your system is to ask:

• Where can warm product meet cool surfaces (condensation risk)?

• Where does dust accumulate and get re-aerosolized?

• What surfaces are “clean side” on paper but shared in practice (boots, forklifts, maintenance tools)?

5) Tie It Back to Aquaculture Outcomes: Stability Beats Heroics

From the farm perspective, reducing pathogens in fishmeal is about reducing variability—in health, survival, and feed conversion—by lowering the odds that pathogens enter (and then persist in) the production ecosystem. Aquaculture-focused feed hygiene discussions often frame this as a controllable lever that supports resilience and performance consistency.

The Takeaway: A Three-Barrier Program

A robust approach usually looks like:

1. Supplier and receiving controls (risk-based)

2. Validated processing lethality (with low-aw realism)

3. Aggressive recontamination prevention and verification (environmental monitoring and trend review)

Thermal processing is critical for reducing pathogen load in fishmeal and often represents the strongest single control in the system, but consistent results depend on the controls wrapped around it. In low-moisture environments, pathogens may not grow, yet they can persist in dust and resident niches and re-enter product streams through condensation events, traffic flow and hard-to-clean transfer points after the heat step. The most reliable programs treat this as a three-barrier approach that supports (not replaces) processing lethality with risk-based supplier and receiving controls, validation that reflects real moisture/aw and residence-time conditions, and disciplined post-process protection through zoning, recontamination prevention and verification designed to find recurring hotspots early. If you want to tighten control while keeping operations practical, contact your clean feed expert today.