The gap between the pellets that “looks fine” and “is fine” is where aquaculture quietly loses money and fish health.
Moisture is the trigger for almost every feed problem. Once moisture climbs above roughly 12%, moulds can take hold and begin producing mycotoxins which are the toxic compounds from Aspergillus, Penicillium and Fusarium fungi. Steam pelleting and extrusion both push water into the pellet during manufacture, so feed leaves the line warm and damp. In hot, humid storage, that’s exactly the wrong starting point.
How Common Is The Problem?
It is a very common problem.
A 2025 global survey analysing 51 mycotoxins across hundreds of feed samples found contamination is almost universal and that the raw materials themselves often arrive sitting near or above the mould line.
90%+ of compound aquafeed samples carried at least one mycotoxin, 7.2% of fish-feed samples exceeded the EU limit for aflatoxin B₁ and 400+ distinct mycotoxins identified in scientific literature.
Mould-spoiled feed is linked to slower growth, higher disease and mortality, and reproductive problems in fish and shrimp and residues can travel up the chain to the human plate.
Packaging Is The Front Line Defense
You can dry feed perfectly and still suffer loss.
Between the mill and the pond, the packaging is the only thing holding humid air away from the pellet. A weak barrier lets water vapour creep in and let the moisture content drifts upward which makes the 12% line crossed in storage rather than on the production floor.
Good barrier sacks usually solve this by layering materials, an oxygen barrier such as EVOH or nylon paired with a moisture barrier such as polyethylene. They protect the feed well. But the catch is that these multi-material laminates are notoriously hard to recycle, and if they end up near water, they don’t break down instead they fragment into microplastics in the very ecosystem aquaculture depends on.
This is the problem PHA biopolymers are built for.
Polyhydroxyalkanoate is insoluble in water and offers strong vapour and gas barrier performance, so it does the core job of keeping moisture out and feed below the mould threshold. Unlike polyethylene films, PHA is certified to biodegrade in marine, soil and compost environments, leaving no persistent plastic behind. In peer-reviewed work, a PHA coating held a film’s moisture below its damage point at 75% relative humidity for two full weeks.
TerraPHA Biotech which is India’s first commercial biopolymer company produces non-GMO PHA designed for exactly this kind of demanding application. For aquaculture, that means feed packaging that defends against moisture and contamination without adding to the plastic burden of the ponds and waterways it serves.
Frequently Asked Questions
At what moisture level does aquaculture feed start to grow mould?
If feed moisture exceeds about 12%, molds can start growing and producing mycotoxins. As steam pelleting and extrusion introduce additional moisture to the feed during processing, it needs to be dried before it is protected from humidity in storage by means of an effective moisture barrier.
What’s wrong with conventional barrier sacks?
Conventional/ Traditional barrier sacks incorporate oxygen barrier films like EVOH or nylon and moisture barrier films like polyethylene. While effective, they have several drawbacks including being made up of multiple materials, difficult to recycle, and if they come in contact with water, break down into microplastics.
How do PHA biopolymers help with feed packaging?
PHA is insoluble in water and offers good vapour and gas barrier performance, so it helps keep feed dry. Unlike fossil-based films, PHA is certified to biodegrade in marine, soil and compost settings leaving no harmful residue in the ponds and waterways aquaculture depends on.
