BMP testingFats, oils and animal by-products

Fish waste — BMP: 3 studies, weighted mean 319 m³ CH₄/t VS

Fish waste is a high-protein and fatty material from fish processing. It gives a large gas potential, but requires control of ammonia, salt and fats and application of the ABP rules.

rating: neutral CH₄ ≈ 66 % (estimate)

Published 8 October 2026Updated 29 October 20263 min readFeedstockData Editorial Team

Illustration: FeedstockData (AI, Google Gemini)

Weighted mean: 319m³ CH₄/t VS
Range: 142–416m³ CH₄/t VS
Records: 3studies
Publications: 3sources
Temperatures: 35 °C, 37 °Cof the test

Methane in biogas

≈60–69% CH₄

High methane content · ≈ 6.6 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (protein-rich (process classification); fat-rich (process classification)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

neutral — editorial rating for biogas plantsNo clear advantages — worth charging a fee for accepting it

Potential per tonne of fresh matter: very high (186 m³ CH₄/t); process risk: fats, protein / nitrogen, salt / sodium. Handling costs: ABP cat. 3.

Why? Rating factors

Potential per tonne +3

+3potential 186 m³ CH₄/t fresh matter (BMP 319 × DM 60 % × VS 97.5 %)

Process stability −2

−1fats: risk of accumulation of long-chain fatty acids (LCFA), flotation and overloading
−0.5protein / nitrogen: risk of ammonia inhibition at higher shares
−0.5salt / sodium: inhibition at high shares

Handling and costs −1

−1ABP cat. 3: pasteurisation at 70 °C / 60 min

Total points: 0 · thresholds: ≥ 2.5 very good, ≥ 1 good, below — neutral; negative with cumulative process risk.

Editorial rating per the methodology · confidence of the rating: medium · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 3 studies

Weighted mean Individual records

Dashed lines are a model curve (first-order kinetics, B(t) = B₀·(1 − e^−kt)); the end point comes from the publication. All curves are model curves.

Cumulative methane production over the test [m³ CH₄/t VS]. The thick line is the weighted mean of all records (319); dots mark the end values given in the publications. Point at the chart to read values; click a legend item to hide or show a record.

Records and sources

Download CSV

Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Noh et al. (2026) DOI	398	35 °C · mesophilic	fish waste (FW), mono-digestion (R6)	end point (model curve)
Cu et al. (2014) DOI	142	37 °C · mesophilic	fish slaughter waste	end point (model curve)
Kouas et al. (2017) DOI	416	35 °C · mesophilic	coalfish	end point (model curve)
Weighted mean	319	arithmetic mean 319, SD 153

Typical composition

Dry matter (DM): 60% (range 60–60)
Volatile solids (VS): 97.5 % DM (range 97.5–97.5)

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: MY-D); dry matter: 1 determination, volatile solids: 1 determination. DM from a single determination – indicative value.

Sources: Cu et al. (2014).

The composition of the raw material varies between batches — for plant calculations use an analysis of your own sample. The calculator inserts typical values automatically.

Process properties

protein-rich
fat-rich
saline
nitrogen-rich
ABP cat. 3
variable composition
editorial classification

Advantages

Methane potential in the Substraty.pl BMP dataset: weighted mean 318.7 m³ CH₄/t VS (SD 153.1; 3 records, 3 sources).
Fish waste co-digested with sisal pulp gave a higher methane yield than either component separately (Mshandete et al. 2004).
High protein and fat content gives a large potential per unit of mass (Mshandete et al. 2004).

Drawbacks and risks

Fish protein releases ammonia, fat releases LCFA (including unsaturated) - risk of methanogen inhibition (Chen et al. 2008).
Waste from marine fish may contribute sodium and calcium; sodium at a high concentration inhibits methanogenesis (Chen et al. 2008).
Spoils very quickly - odour and changes in composition (Mshandete et al. 2004).

Co-digestion — what to combine it with, what to watch out for

combines well
substrates: carbon-rich — e.g. Wheat straw, Maize silage (whole crop), Cereal straw (unspecified), Willow (short rotation), Cardboard and paperboard
Adding a carbon-rich/fibrous material improves C/N and yield (sisal 67%).^[1]
caution
substrates: protein-rich — e.g. Food waste, Municipal sewage sludge (mixed), Poultry manure, Organic fraction of municipal solid waste, Grass clippings
Fish + other protein: ammonia.^[2][3]

Dosing

In the batch study the best mixture was 33% fish waste and 67% sisal pulp (16.6% DM of the feed). This is an example for sisal, not a standard; start with a low share in a mix with a fibrous substrate.

Introduce gradually, starting with a small dose and monitoring the process (e.g. FOS/TAC, pH, gas composition).

Practical requirements

ABP cat. 3 (Art. 10 of Reg. 1069/2009; admitted to biogas plants by Art. 14): hygienisation before the digester in a mandatory unit: shredding to a maximum of 12 mm, temperature throughout the mass of at least 70 °C for at least 60 min without interruption (Reg. 142/2011, Annex V Ch. I Section 1 and Ch. III Section 1); the installation requires approval by the competent authority (Art. 24(1)(g) of Reg. 1069/2009).
Do not feed hygienised substrate into the digester hot (FNR 2010, Ch. 3: hygienisation).

Sources of the process data

The co-digestion calculator will assess a specific mixture containing this substrate.

What it is and where it comes from

Fish waste arises in fish processing plants, in the slaughter of farmed fish and in markets: heads, bones, skins, viscera, fins and unusable trimmings. In Poland there is less of it than in coastal countries, but it occurs locally, for example in fish farming and processing. The dataset includes several records: fish waste from South Korea (the text of a preprint), waste from fish slaughter, and saithe.

Properties relevant to digestion

Fish consist mainly of water, protein and fat. The decomposition of protein releases ammonia, and of lipids long-chain fatty acids, including unsaturated ones, which strongly affect methanogenic microorganisms. The waste may contain salt (especially with marine fish and salted products), which increases the salinity of the digester. The material is very prone to rapid spoilage and generates unpleasant odours, so it requires rapid processing or cooling. The composition is heterogeneous, because it depends on the species, the part of the fish and the season.

How to read the spread of results

The records concern different materials: a mixture of waste from processing, waste from fish slaughter and a single fish species. Differences in the amount of fat and bone, in the degree of grinding, in sample preparation and in the substrate-to-inoculum ratio are large. For high-protein substrates the inoculum adaptation time also matters. One of the records comes from the text of a preprint, which may not be the final version of the article, as marked in the description of the record.

In biogas plant practice

Fish waste is an animal by-product. Its use requires classification of the category, appropriate treatment (usually shredding and pasteurisation for category 3 material), documentation and compliance with the installation's permit. In the technology, the key points are a limited share in the feed, mixing with a substrate of low nitrogen content, control of ammonia, salinity and volatile fatty acids, and good odour extraction. Because of the variable composition, it is worth carrying out your own BMP test before contracting deliveries. Prior shredding and homogenisation also help, because they allow the material to be distributed evenly in the digester and limit local overloads, which in the case of proteins and fats end in a rapid rise in ammonia.

Methodology in brief

BMP is the amount of methane obtained from volatile solids (VS) in a batch test, given in m³ CH₄ per tonne of VS (numerically the same as NmL CH₄/g VS in the publications) and converted to normal conditions (0 °C, 101.325 kPa). The weighted mean gives each publication a total weight of 1, split equally between its results for the substrate — a paper testing twenty varieties does not outweigh a paper with a single sample. In inter-laboratory programmes the unit is the laboratory (total weight 1), and within it the weight of a test grows with the number of bottles (replicates). Results after pretreatment (e.g. thermal, chemical, enzymatic) are shown separately and are not included in the mean.

Solid lines are curves measured in the tests. Where a publication gives only the final result, we draw a first-order kinetic model, B(t) = B₀·(1 − e^−kt): only the end point comes from the publication, and the shape of the curve serves purely as visualisation — do not read the production on a particular day from it. For this substrate k = 0.091 d⁻¹ was assumed (no kinetic data for the group – the median of all available rate constants k (93 values) was used).

The statistics describe the spread of published results — a descriptive compilation, not a meta-analysis or a guarantee of plant yield.

Full methodology and correction policy

Bibliography

All sources of the site: bibliography.