Composting Fish Waste: Tips On How To Compost Fish Scraps

by johnah on November 26, 2020

Composting Fish Waste: Tips On How To Compost Fish Scraps

How to Make Compostable Fish Waste?

Fish waste is one of the most useful things for making compost. There are many different ways to make it. You may have heard about using fish guts or other parts of fish in your backyard compost pile.

But what if you don’t want to do that? What if you want to make compost from the waste of your favorite fish?

There are two kinds of fish wastes which can be used for making compost. These are the blood and liver wastes. Blood and liver wastes come from any kind of fish including salmon, trout, herring, sardines etc. They can either be dried out or crushed into small pieces before being added to the soil. Both types of fish wastes can be composted in the same way. The only difference lies in the size of the piece of fish waste that you need to bury.

Blood Wastes: Small Pieces (1-2 cm)

Liver Warts: Large Pieces (3-4cm)

Blood and Liver Waste Composting Methods

The following methods will work well for both blood and liver wastes. The only difference is that small pieces of blood waste need to be buried under 1-2 cm of soil, while large pieces of liver wastes need to be buried 3-4 cm deep.

Fish Composting with Grass Clippings

This method is suitable for people who have access to free grass clippings. This involves digging a trench in which you spread grass clippings and burying the fish waste 1-2 cm deep.

Grass clippings will act as a mulch and prevent most of the fish waste from being visible. This method should be done in the spring or in the fall when there is little chance of the ground freezing.

This is how to make fish waste compost using grass clipping:

1. Dig a trench that is about 20-30 cm deep and about 40 cm wide.

2. Spread grass cuttings on the bottom of the trench.

3. Place broken down fish waste (1-2cm pieces) on the grass cuttings.

Composting Fish Waste: Tips On How To Compost Fish Scraps -

4. Spread another layer of grass cuttings on top.

5. Continue layering the trench until you are about half way full.

At this point the trench should be about half grass and half fish waste.

6. Continue adding layers of grass cuttings until the trench is full (about 80% grass and 20% fish waste).

7. Cover the trench with soil and water it in.

If the fish waste is fresh, then you will need to cover the trench with plastic and add a couple of shovels of soil on top every few days. This will help to prevent any foul smells.

If the fish waste is dry, then you should not need to do this. The compost generated from this method should be ready in about a year.

Fish Composting in an Existing Compost Pile

This method is suitable for people who already have a compost pile set up. This involves adding fish waste to an existing compost pile 1-2 cm at a time.

Each layer of fish waste should be covered with a layer of grass cuttings or other organic matter to prevent smelling. This method will also take about a year to produce compost.

The key to successful composting is to keep the pile moist, but not wet. If the compost pile starts to smell, then you have added to much organic matter and the pile needs to be “turned”.

Composting Fish Waste: Tips On How To Compost Fish Scraps - Image

This means that you need to take your pitchfork or shovel and turn the contents of the pile upside down.

This method produces the best quality fish waste compost (further info in next section on how best to use the finished compost).

If you do not want to make your own fish waste compost, then you can buy it from a nursery or online. Before you buy it, you need to know exactly what is in the compost before you use it.

Make sure that the ingredient list states that it is just organic matter and that there are no chemical pesticides or other additives. You do not want to add chemical pesticides or additives to your own compost heap.

The best way to get good quality fish waste compost is to make your own. It’s pretty easy to do and the following is a step by step guide.

If you don’t have space or time to make your own, then follow the advice given in the above link on how to buy quality fish waste compost that has no additives or chemical contaminants.

How to Use Fish Waste Compost

The most important thing with this type of compost is to make sure that it does not come into contact with a plant’s roots. This means that it must be used as a soil amendment and not as a top dressing.

It also is not suitable as a potting mix ingredient.

You can use the finished compost in your garden or farm land in the following ways:

As a surface mulch in vegetable gardens, flower beds and lawns. Spread the compost about 5-10 cm deep over the area to be treated.

As a soil amendment to be worked in above and below the ground. Work compost into the top 15-20cm of soil before planting your garden bed or sowing seeds.

The following is a step by step guide on how to plant a container garden using composted fish waste:

1. Dig a hole in the shape of a square, triangle, circle or any other shape you can think of (can be smaller than a golf ball)

2. Fill the hole with water and let it seep into the soil (give it about 10 minutes)

3. Fill the hole with compost

4. Plant your seeds or plant (ensure you do not get compost in direct contact with the roots)

5. Water the plant well

6. Repeat Step 1-5 for any other plants in your container

7. Water your plants at least once every 2-3 days (more often in hot weather)

8. Harvest when plants are ripe

9. Repeat steps 1-8 for next crop

The amount of plants you can grow in containers using this method is limited only by the size of the container, the amount of compost you have, the type of plant grown and how often you water (don’t want your container to overflow or your plants to rot due to lack of water). If you want to grow more than one type of plant in a container, then make sure you have enough compost for each type or use another growing medium.

You could use traditional potting mix for any plants that require rich soil, just ensure the mix is well drained and that you add some grit or gravel to the bottom of the container to improve drainage.

When using this method with multiple plant types, it is best to stagger your plantings over a week or so. For example, if you are planting 3 types of plants: Tomatoes, Beans and Peas, plant the tomatoes first, wait a week and then plant the beans, another week and you can plant the peas.

This method can also be used to grow herbs such as Chives, Coriander and Parsley in small containers (think cups) on your window sill. Just remember to give them lots of water, and don’t expect giant quantities – just enough for your cooking needs.

A Good Resource For Information On Growing Specific Vegetables And Herbs Is The ATTRA (national sustainable agriculture information service) site. They have a lot of information on many different topics.

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I have listed some of their publications here:

ATTRA Publications – Publications Covering A Wide Variety Of Sustainable Agriculture Topics.

ATTRA Sustainable Vegetable Production – Vegetable Booklet.

ATTRA Publications Covering Aquaculture – For Varity Of Aquatic Species Including Catfish, Basa, Trout, Tilapia And Many Others.

ATTRA Publications Covering Herbs – Includes Topics Such as Growing, Marketing And Processing Herbs.

ATTRA Publications Covering Organic Production – A Wide Range Of Topics Including Soil Building, Composting, Weeds, Pests And Much More.

ATTRA Publications Covering Small Farms – Primarily Focused On The Northern Plains (ia, Mo, Nd, Oh, Ks And Nm), But Can Be Applied Elsewhere.

ATTRA Publications Covering Native American Farming Traditions – Includes Agriculture Traditions Of The Iroquois, Oglala Lakota, Cherokees, Navajos And Others.

ATTRA Publications Covering Pasture-Based Livestock Systems – Includes Beef Cattle, Sheep, Goats And Horses.

ATTRA Publications Covering Rangelands – Primarily Focused On Ks, Nm, Ok AndTx.

ATTRA Publications Covering Sheep – Primarily Focused On Marketing Wool And Mutton.

ATTRA Publications Covering Specialty Crops – Includes Topic Such As Asian Vegetables, Fruit, Greens And Herbs.

ATTRA Publications Covering Specialty Crops (fruit) – Includes Berries, Grapes, Citrus And Other Topics.

ATTRA Publications Covering Sugar Beet And Sugarcane – Primarily Focused On The North Central Region Of The US (Wi, Mn, Nd, Id, Sd, Ne).

ATTRA Publications Covering Tomatoes – Primarily Focused On The Northeastern Region Of The US (Ma, Ny, Nj).

Yours Truly,



If you need a good recipe for Garlic Soup, let me know and I’ll send you one.

Gardening Ebooks

Garden Guide – A beginners guide to gardening. Covers planning, soil preparation, planting, pest control, composting and much more.

Container Gardening – How to grow vegetables, herbs, fruits, and berries in pots.

Raised Bed Gardening – How to prepare your soil, plant, and maintain a successful garden.

Seed Starting – Start your own seeds and grow healthy plants. Includes information on seed starting containers, seed starting mediums and more.

Home Canning – How to can your home grown produce. Includes information on what can be canned, water bath canners, pressure canners and more.

Composting Fish Waste: Tips On How To Compost Fish Scraps |

Preserving Meat – How to preserve your hunts with salt, ice, and smoke.

Medicinal Herb Garden – Learn how to grow your own medicinal herbs.

Gardening Videos – Watch our videos related to gardening.

Gardening News

Are You Ready For This Much Tomato?

I’m sure you have seen these amazing huge tomato plants. They are loaded down with so much fruit, they are practically bending down to the ground. These are a favorite topic of garden show judges and people like me who are fascinated by over-the-top gardening. There is even a special heirloom variety called the Mazda Monster which was grown by a Mr. Mazda back in the late 1800’s and is still grown today. If you have the room, this would be an awesome plant to grow. It gets so big and loaded down with fruit that it can even take over a porch or patio.

One thing that many people don’t realize is that a plant like this does take a lot of extra care. It needs a sturdy, strong trellis to hold up all of that weight.

Sources & references used in this article:

Meat waste as feedstock for home composting: Effects on the process and quality of compost by F Storino, JS Arizmendiarrieta, I Irigoyen, J Muro… – Waste Management, 2016 – Elsevier

Evaluation of farm plot conditions and effects of fish scrap compost on yield and mineral composition of field grown maize by WF Brinton Jr, MD Seekins – Compost Science & Utilization, 1994 – Taylor & Francis

Mercury and Composting Fish Waste–A Pilot Project by M Hudson – Project Report, 2008 – Citeseer

Safe and Legal Fish Waste Composting in Alaska by I Chambers – 2011 –



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