The Complete Guide to Using Fish Emulsion Fertilizer

Fish emulsion fertilizer is a type of plant feeder that you can buy or make at home. It contains nitrogen, phosphorus, potassium, and other nutrients vital for plants and soil. However, even though these fertilizers are usually pretty straightforward to use, it’s still a good idea to learn a bit more about them before applying them to your meticulously-grown plants.

Fish emulsion fertilizer is a mixture of fish, molasses, organic matter, and water. Once you’ve mixed everything and let it sit for a few weeks, you can dilute it with water and use it as a fertilizer. If you don’t want to make it, you can buy ready-made fish emulsion online or in a garden center.

Fish emulsion is an excellent organic fertilizer, and this article will discuss how to make it in greater detail. It will also discuss how to use it and why it’s beneficial for your plants and soil.

What Is Fish Emulsion Fertilizer?

Fish emulsion is a plant fertilizer made primarily of fish, molasses, and water. You can also add organic matter, such as sawdust or grass clippings–these help absorb the foul fishy smell, but they’re not necessary.

The fertilizer can consist of different fish parts. Some people like to use fish waste (i.e., the parts that aren’t edible, like fish guts). Others like to use whole fish. You can also add other ingredients like crabs if you have any leftovers.

How To Make Fish Emulsion Fertilizer

Making fish emulsion is pretty straightforward. It won’t take too long if you have everything you need. However, you will have to wait at least a few weeks until you can use it–you need to give it time to break down and turn into a liquid, and you may need to let it sit for up to a few months.

To learn more about making fish emulsion fertilizer, read the steps below.

Gather Whole Fish or Fish Waste

Firstly, you’ll need to gather your fish products. If you have fish waste at home, you can use that. But if you need to find it somewhere, you can ask around at local fish markets or stores–most would be happy to give you their fish waste because they’ll be throwing it away anyway.

Alternatively, if you enjoy fishing, you could go out and get some yourself. Make sure you get enough fish. The amount you need will depend on how many plants you want to feed and how much fertilizer you want to make.

If you would like to explore your options for turning fish waste into fertilizer, check out my article: Can You Turn Fish Waste into Fertilizer? 7 Facts

Get a Large Bucket or Trash Can

Next, you’ll need to get a large bucket or trash can. You’ll be using it to mix everything. It’s essential to use one that has a lid because you’ll need to cover it for a few weeks. If you want to make a large portion of fertilizer, it’s best to use a large trash can. But a small or large bucket should be OK if you only make a small amount.

If in doubt, choose one bigger than you think you’ll need. 

Add the Fish to the Bucket/Trash Can

Once you’ve got your bucket or trash can, you can add the fish into it. This part is naturally going to be smelly, so be prepared! You can add all the fish at once, and there’s no need to cut them into smaller pieces–they will decompose no matter how big or small the parts are.

If you’re planning on feeding lots of plants with this fish emulsion fertilizer, you’ll naturally want to add lots of fish.

Pour Molasses Into the Bucket/Trash Can

The next step is to add molasses. Be sure to use unsulfured molasses, which doesn’t contain additives. You need this ingredient because the sugar in molasses feeds the bacteria in the emulsion, which is essential for decomposition. It also helps to mask the foul odor.

If you’re only making a small portion of fish emulsion, you can use a few teaspoons of molasses. However, if you’re creating a large mixture, it’s best to use an entire bottle of the stuff.

Add Organic Matter

This step is optional. You can make fish emulsion without adding any extra organic matter, but adding it will help keep the bad smells at bay. Examples of organic matter you can add to your fish emulsion include:

  • Grass clippings
  • Dried leaves
  • Sawdust

You can even use a newspaper. If you want to add any of these to your emulsion, you can throw them into the bucket/trash can with the fish and molasses.

Fill the Rest of the Bucket/Trash Can With Water

Next, you’ll want to add water to the bucket. That way, the fish waste can decompose into the water over the coming weeks, creating a liquid you can dilute with more water when you want to fertilize your plants.

The water doesn’t have to be at a specific temperature, so you can use tap or bottled water.

Stir Everything

Once you’ve added the water to the mixture, you can stir everything using a stick. Make sure everything is mixed thoroughly before leaving the mixture alone. You’ll likely find it difficult to stir while dealing with the smell, but you should only need to stir for a few seconds.

Once everything is mixed well, you can move on to the final step.

Cover With a Lid

When everything is done, it’s best to cover the mixture with a lid. Keeping it covered will help hide the smell, which is essential if you want to keep flies and pests away from your garden. However, the emulsion will need some air, so making some tiny holes in the lid is a good idea.

That way, the mixture can have better access to oxygen but won’t attract pests.

I’ve written an in-depth guide about whether fish emulsion fertilizer attracts pests. Don’t miss it: Does Fish Emulsion Fertilizer Attract Pests?

How To Use Homemade Fish Emulsion Fertilizer

Now that you know how to make fish emulsion fertilizer, you’ll need to know how to use it. You must have given the emulsion mixture enough time to sit and decompose before using it on plants. Otherwise, it won’t be as effective. 

You’ll also notice that once the emulsion is ready for use, the smell won’t be as potent as it used to be.

Read below if you want to know how to use homemade fish emulsion (once it’s ready to use, of course!).

Remove the Lid and Stir

Firstly, you should remove the lid from the emulsion. Once you remove it, you shouldn’t notice a pungent smell. Although it will likely still smell slightly fishy, it shouldn’t be unbearable. Once you’ve removed the lid, you can stir the mixture with a stick or other appropriate object.

Be sure to stir it thoroughly before moving on to the next step.

Place the Desired Amount of Emulsion in a Watering Can

After stirring, you can place the desired amount of emulsion in a watering can. Using a watering can is best because you’ll need to dilute the emulsion with water before applying it to the plants. However, you can use anything that will work, like a bottle.

Scoop the emulsion into the container. It’s OK if you don’t use all the emulsion in one go–it can last at least a few months in the bucket/trash can, so you can go back to it every time you want to apply more fertilizer to the plants. 

Dilute With Water

Next, you want to dilute the emulsion with water. Generally, mixing a gallon (3.8 liters) of water with every 1-2 tablespoons of emulsion is best (this goes for most liquid fertilizers). If you want the fertilizer to be more concentrated, use less water or more tablespoons of the emulsion. If you want it to be less concentrated, use more water or fewer teaspoons of the emulsion.

But for the most part, it’s best to use the recommended ratio.

Pour on Plants

Once it’s diluted, the mixture is ready to use! You can pour the fish emulsion fertilizer directly onto your plants’ soil. Since there is water in the mixture, you won’t need to water your plants afterward. 

Although most organic fertilizers are slow-release, fish emulsion is fast-release because the soil and plants absorb liquids quickly. So, when you feed your plants with fish emulsion fertilizer, you should see results quickly.

Can You Buy Pre-Made Fish Emulsion Fertilizer?

You can buy pre-made fish emulsion fertilizer online or in garden stores and centers. Although buying pre-made fish emulsion fertilizer requires much less effort, it is more expensive. If you want to save money and have some time on your hands, making fish emulsion at home is best.

Most pre-made fish emulsion fertilizers you can buy contain nitrogen and a low amount of phosphorus and potassium. 

For example, this Liquinox Fish Emulsion Fertilizer (available on contains 5% nitrogen and 1% phosphorus and potassium–this makes it a great source of nutrients for many plants, shrubs, and trees. It also contains essential micronutrients like zinc and iron.

Most pre-made fish emulsion fertilizers are 5-1-1. Here is what these numbers mean:

  • The first digit (in this case, 5) indicates the ratio of nitrogen in the fertilizer.
  • The second digit (in this case, 1) shows the ratio of phosphorus in the fertilizer.
  • The third digit (in this case, 1) indicates the ratio of potassium in the fertilizer.

You’ll see “5-1-1” on the front packaging of most fish emulsion fertilizers. 

So, pre-made or homemade fish emulsion fertilizers are an excellent choice if your plants are primarily lacking nitrogen.

Using Pre-Made Fish Emulsion Fertilizer

How you use pre-made fish emulsion will depend on what the instructions say. But in most cases, you’ll use it in the same way you’d use homemade fish emulsion fertilizer.

Below is a brief guide on how to use pre-made fish emulsion fertilizer (the measurements are recommendations based on the instructions of the Amazon product listed in the previous section):

  1. Read the instructions. If there are instructions on the packaging, read them first. You can follow the rest of this guide if there aren’t any.
  2. Mix 1-2 tablespoons of fertilizer with a gallon (3.8 l) of water. If using the mixture for outdoor plants and vegetables, 1 tablespoon is fine. If using it for larger plants like trees, use 2. For smaller potted plants, you can use ½ teaspoon with a quart (0.95 liters) of water.
  3. Apply to the roots. You want to apply the fertilizer mixture generously across the roots of the plants or vegetables. 
  4. Reapply as needed. Since all liquid fertilizers (including fish emulsion fertilizer) are fast-release, you’ll need to use them every few weeks.

Why Fish Emulsion Fertilizer Is Beneficial

You might wonder why you should use fish emulsion fertilizer over other fertilizers. After all, it takes some time and effort to make it, and it doesn’t smell very good initially! 

But despite all this, fish emulsion helps plants grow and thrive, and it’s inexpensive if you can make it at home.

Below are some of the top reasons why fish emulsion fertilizer is beneficial.

Plenty of Nutrients

First, and most importantly, fish emulsion fertilizer contains plenty of nutrients that are excellent for the health of plants and vegetables. For example, fish emulsion is high in nitrogen, which is vital for plant growth and development. Therefore, using fish emulsion can give your plants the boost they need during the growing season.

In addition to nitrogen, fish emulsion fertilizer also contains nutrients like:

  • Phosphorus
  • Potassium
  • Zinc
  • Calcium
  • Magnesium


Thankfully, there are no synthetic chemicals in fish emulsion fertilizer, so it’s completely organic. Therefore, it’s less likely that you’ll burn or damage your plants if you use too much of it. While accidentally using too much fish emulsion fertilizer can harm plants, it won’t be as harmful as doing the same with a chemical fertilizer.

So, if you want your garden to remain organic and natural, fish emulsion fertilizer is an excellent choice.

Fish Emulsion Fertilizer Makes Use of Waste

If you have leftover fish, you’ll need to dispose of it. However, if you make fish emulsion fertilizer, you can use those leftovers to help your garden thrive. It’s an excellent way to use something you would otherwise throw in the trash.

It can also help shop owners if you collect fish waste from them. Instead of dumping all the fish waste, you can take it out of their hands and put it back into the earth’s soil.

Making It at Home Is Cost-Effective

Another thing to consider is cost. While store-bought fish emulsion fertilizer can be expensive, making it at home is exceptionally cheap. The most costly part is the fish, but you might be able to get fish waste for free from a fish shop or market. 

So if you want your plants to thrive without breaking the bank, creating a fish emulsion fertilizer at home is a great choice.

How Often Should You Use Fish Emulsion Fertilizer?

You should use fish emulsion fertilizer once every 1-3 weeks, depending on the quantity of nutrients your plants need and how strong the emulsion is. You should use it once weekly if it’s a weak emulsion (for example, 2-1-1). 

Using it every 2-3 weeks should be enough if it’s stronger than this. Of course, you’ll only know the ratio of nutrients if you’re using store-bought fish emulsion fertilizer. If using homemade fertilizer, you should use it once every 2-3 weeks to avoid the risk of over-fertilization.

You only need to do this during the growing season–there’s no need to apply fish emulsion fertilizer during winter when plants are dormant.

The only times you might want to use fish emulsion fertilizer during winter is if the plants are evergreen or the weather is hot all year round. 

Can You Use Fish Emulsion Fertilizer on All Plants?

You can use fish emulsion fertilizer on all plants because it contains all the essential nutrients they need. However, you shouldn’t use it if your soil already has high nitrogen levels. Fish emulsion fertilizer is high in nitrogen, so adding too much can cause damage to plants.

For the most part, you can use fish emulsion fertilizer on all plants, including:

  • Vegetable plants (tomatoes, lettuce, cucumbers, etc.)
  • Flowering plants (buttercups, roses, daffodils, etc.)
  • Trees (evergreens and deciduous trees)
  • Shrubs 
  • Grass

So if you’re looking for a general fertilizer appropriate for all plants in your garden, it’s worth considering fish emulsion fertilizer.

Is Fish Emulsion Fertilizer Enough for Plants?

Fish emulsion fertilizer is enough for plants because it contains vital nutrients and feeds plants quickly. You can use it instead of other fertilizers, or you can use it in between granular fertilizer applications. 

If your soil isn’t lacking too much in nutrients, a fish emulsion fertilizer by itself should be more than enough to keep your plants thriving during the growing season. However, fish emulsion won’t be enough if your soil needs lots of nutrients or higher levels of potassium or phosphorus.

In that case, you’d need to use a more specific fertilizer. You can also use fish emulsion fertilizer as a pick-me-up between the main feedings (which generally occur twice a year).

Final Thoughts

Fish emulsion fertilizer is excellent for plants due to its high nitrogen content. It also contains phosphorus, potassium, and some essential micronutrients. To make it, all you need is some fish waste, water, molasses, and a bucket or trash can.

Once it’s ready to be used, you can dilute it with water and apply it directly to the roots of your plants. If you use store-bought fish emulsion fertilizer, you can mix it with water immediately.

You should use fish emulsion fertilizer once every 1-3 weeks to keep your plants healthy and thriving.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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