How to Make Fish Amino Acid (FAA): The KNF Nitrogen Input

Fish amino acid is the Korean Natural Farming system's primary nitrogen input. It is made by fermenting fish material with brown sugar — the same osmotic extraction process used for FFJ and FPJ, but with fish rather than fruit or plant shoots. The result is a dark, concentrated liquid rich in free amino acids that the plant can absorb directly through root amino acid transporters, bypassing the slow soil mineralization process that conventional organic nitrogen sources require.

FAA is a vegetative-stage input. It is not applied during flower — the goal of FAA is to rapidly supply nitrogen for the protein synthesis and chlorophyll production that drives vigorous vegetative growth. Once the plant transitions to flower, the input switches to FFJ, which is optimized for secondary metabolite support rather than vegetative nitrogen loading.

What FAA contains

Fermented fish breaks down in a predictable pattern. Fish tissue is protein-dense, and those proteins consist of amino acids linked by peptide bonds. The osmotic sugar draws out the intracellular fluid, and the fermentation process — driven by native microorganisms in the fish tissue and from the air — produces proteases that cleave those peptide bonds. After 7-10 days, a significant fraction of the protein content has been converted to free amino acids in solution.

The specific amino acid profile depends on the fish. Fish high in protein — dark oily fish like sardines, anchovies, catfish and salmon — produce FAA with higher total amino acid concentrations than white fish with lower protein content. The traditional KNF guidance to use "dark, oily fish" reflects this: more protein, more amino acids in the finished extract.

FAA also contains: organic acids from fermentation, trace minerals from fish tissue (phosphorus, calcium, iron, iodine), B vitamins from the fermentation process and simple compounds from the fermented fat fraction. The amino acid content is the primary value, but FAA is not a single-compound input.

Materials

• Fish material: whole small fish or fish scraps (heads, bones, entrails). Sardines and anchovies work well — they are small, oily, protein-dense and inexpensive. Any fresh fish works.
• Brown sugar: equal weight to the fish material
• A glass or food-safe plastic container with a lid (not airtight during fermentation)
• Cheesecloth or fine strainer

On freshness: Use fresh fish, not fish that has already decomposed significantly. A fish that smells of ammonia before fermentation has already lost much of its amino acid content to bacterial breakdown without the controlled osmotic extraction process. Fresh fish has a clean oceanic smell, not an ammonia smell.

The process

Step 1 — Weigh the fish and sugar. The ratio is 1:1 by weight — equal parts fish and brown sugar. For most home setups, 500g of fish and 500g of brown sugar is a manageable starting batch.

Step 2 — Layer in the container. Add a layer of sugar to the bottom of the container, then a layer of fish, then more sugar, alternating until all material is in. End with a thick sugar cap on top. The sugar cap is important — it creates the osmotic environment and inhibits the surface aerobic organisms that would otherwise compete with the fermentation you want.

Step 3 — Cover and leave. Cover with cloth (not airtight) and leave at room temperature, 65-80°F, for 7-10 days. Warmer ferments faster; cooler ferments slower. Stir or agitate once daily — this distributes the liquid as it forms and ensures the fish tissue stays in contact with the sugar environment.

The smell during fermentation is strong. This is normal. Find an outdoor location, a garage or anywhere you can set it and leave it. The smell will be present throughout the fermentation period and will taper after straining.

Step 4 — Strain. At 7-10 days, the liquid will have accumulated at the bottom, the fish tissue will be significantly broken down (soft, degraded), and the sugar will have mostly dissolved. Strain through cheesecloth, squeezing the remaining solids to extract the liquid. Discard the spent fish material.

Step 5 — Check and store. The finished FAA should be dark brown to black, strongly aromatic (fermented fish with sweetness from the sugar), and pH around 3.5-4.5. It will smell intensely but it should not smell like ammonia — that indicates spoilage rather than successful fermentation.

Store in a sealed container. Refrigerated, FAA keeps 6-12 months. At room temperature in a cool dark location, 3-6 months. It will continue to develop a slightly stronger smell over time, which is normal.

Troubleshooting

Ammonia smell at any point: Possible causes are fish that was already too far degraded before use, fermentation temperature too warm (above 85°F), or insufficient sugar to create the osmotic environment. A strong ammonia smell means the protein has broken down via putrefaction rather than enzymatic hydrolysis. Discard and start fresh with colder conditions and fresh fish.

No liquid forming after 5 days: The sugar is not pulling liquid out effectively. Possible causes: fish was too dry, the ratio was off, or temperature was too cold. Stir well to ensure fish is in contact with the sugar. Add a small amount of water (10-15% of fish weight) to help if needed.

Kahm yeast on surface: A flat white film, not fuzzy mold. Skim it off and continue. This is the same yeast that appears in vegetable ferments and does not ruin the batch.

Fuzzy mold: Discard. This means the sugar cap failed or the batch was contaminated. Start fresh.

How to apply

Dilution: 1 mL per liter of water (1:1000). This is a stronger effective concentration than FFJ (1:500) — FAA is potent and a little goes a long way.

Timing: Vegetative stage only. Apply once or twice per week during active veg when the plant is growing rapidly and nitrogen demand is high. Stop FAA at or before the transition to flower.

Application: Soil drench is primary. Foliar at the same dilution is sometimes used during early veg for fast response to nitrogen deficiency signs — pale green new growth, slow development.

Caution: Do not over-apply FAA in late vegetative or at the transition to flower. High free amino acid nitrogen at this stage can extend vegetative programming and delay or complicate the transition to reproductive development. FAA is a veg input. When the plant signals flower, the input switches.

The flowering stage has different requirements — that is where FFJ takes over from FAA in the KNF program. Our FFJ formulas are built specifically for that window. [Join the waitlist to be notified when they launch].