6 Best Fish Emulsion Fertilizers | How And When To use them

The long-established method of using fish to fertilize crops goes back as far as the ancient Roman Empire and indigenous cultures in the Americas.

The concept of taking from the earth to give back to it all began when farmers observed how well corn and other crops fared when fish remains were left to decompose near them. Thus began a practice that continues to this day. 

Thanks to science, we now understand why fish material affects crops so positively. Fish contain highly beneficial amounts of nitrogen, potassium, and phosphorus, plus other vital trace elements. Exactly what plants require to thrive!

Here’s my ‘deep dive’ into what fish emulsion is made up of and how to go about choosing a product that will meet your gardening and growing requirements. Plus, my pick of the 6 best fish emulsion fertilizer options on the market.

What Is Fish Emulsion Fertilizer? 

These formulas are made from bits left over after fish fillets are cut and prepared as food for us. This includes the bones, scales, and skin as well as guts. This practice of ‘nothing going to waste’ perfectly complements our efforts toward sustainability in the garden.

This organic fertilizer comes in a number of forms, from concentrated liquids to powders, in either pure emulsion form or as a hydrolysate. Hydrolysate, in this case, means to break down salt content with water while keeping beneficial oil and proteins intact. 

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How Is Fish Plant Food Made? 

According to Iowa State University, fish emulsion is made by taking the aforementioned leftover bits and processing them into a thick slurry in an industrial-grade blender. Some manufacturers add water to this mixture to make application easier and to help lessen its famously pungent aroma. Others allow this slurry to dry out and pulverize it into a powder that can be used as either a slow-release fertilizer or as a water-soluble option. 

Fish Fertilizer Powder 

Fish emulsion powder is a professional-grade plant feed versatile enough to be used as a slow-release option when worked into the soil or a quick-acting choice when mixed with water and applied directly to the roots.

Made by drying out residual fish material and grinding it down to a fine, brown-green powder, it comes in either a loose powder or concentrated cakes for easy use and storage, usually minus a strong smell. 

Organic Liquid Emulsion Fertilizer 

The liquid form has a far faster absorption rate than powdered alternatives as nutrients are carried directly to the roots for immediate feeding. This option is made by simply adding water for use when watering or as a foliar spray. Or, by processing the original slurry through a hydrolyzing process (fish hydrolysate), whereby essential oils and proteins are protected from being watered-down. 

Fish Fertilizer Benefits 

In addition to all the nutritious goodness of this concoction, the most highly prized benefit is the way that your plants access it. Access wouldn’t be possible if it weren’t for all those lovely micro-organisms that are present in the soil. Fungi and helpful bacteria consume the fish waste and re-release it in a form that can be absorbed by your plants. 

Once they do, they benefit from a purely organic, burn-free source of nitrogen (provided that your soil isn’t already rich in it), phosphorus, and potassium along with secondary nutrients like calcium and magnesium. 

Indoor Plants 

Once your houseplants have depleted the soil of nutrients, a dry form may possibly be the best option for you. The liquid kind may be a bit too ‘aromatic’ for indoor spaces (but outdoors, it works like magic!).

Fish fertilizer will provide your plants with all the vital nutrients and trace elements they need. Being organic, you can rest easy that you’re not introducing strong chemicals into your home. 

Flowering  Plants

While the potassium and phosphorus in this encourages an abundance of blooms, the high nitrogen content keeps each bud in bloom for longer while extending overall bloom time for the plant.

The organic N-P-K of fish fertilizer supports strong root formation, which results in foliage and buds with vibrant color and resistance to pests, disease, and environmental stressors. This means it makes a fantastic fertilizer flowering for fruit and vegetable plants. 


When proper dosage recommendations are followed, a fish emulsion has the potential to produce higher yields in crops like tomatoes. This is especially true in cooler weather regions, where it breaks down in the soil at a consistent, advantageous pace. (As opposed to chemical or manure-based fertilizers that break down more slowly as the temperature drops.)

The extra calcium, magnesium, and other trace minerals also prevent bottom rot on tomatoes, a disease that commonly occurs if plants are over-watered. 

Fish Emulsions Vs Seaweed 

When considering an organic source of nutrients, some question the difference between this and seaweed fertilizer. Both are rich in what plants need but what makes the difference is often contained in your soil. Seaweed contains adequate levels of nitrogen but they’re not particularly high, making it perfect to add to compost.

If you don’t use compost and you’re looking for higher levels of nitrogen, then fish emulsion would be a more effective option.

N-P-K Ratio 

Indoor and outdoor plants flourish with the combination of macronutrients found in a fish emulsion.

  • Nitrogen (N) – for healthy foliage and bloom longevity
  • Phosphorus (P) – for robust roots
  • Potassium (K) – for durable resistance to disease is a great starting point for your plant feeding program

Sadly, few organic compounds offer this much nitrogen, aside from smelly manures.  However, materials like eggshells and coffee grounds can be added for extra nutrients.  


Fertilizer labels display a three-numbered ratio, known as an N-P-K. This ratio indicates the fertilizer’s proportions of nitrogen, phosphorus, and potassium. Example: 5-10-5 means 5% nitrogen, 10% phosphorus and 5% potassium. 

Best Fish Emulsion Fertilizers

Fish Emulsion Fertilizers Reviewed

Fish fertilizers offer a natural and gentle approach to feeding your plants. Without question, they can be one of the best ways to ensure beautiful produce, healthy foliage growth, and lush blooms. But with so many products on the market, each having seemingly unique benefits, it can be confusing to know which is going to perform well.

Product testing and review research takes time, effort, and money, so to make life a little more convenient for you, I’ve done the leg-work and carried out some extensive testing of my own.

I’ve included consumer experiences from all across the gardening spectrum as well as my first-hand user experience and years of gardening knowledge and expertise.

1. Ferti-Lome Fish Emulsion Fertilizer 5-1-1 

Ferti-Lome Fish Emulsion Fertilizer

This liquid option from Fertilome is formulated to supply a natural release of essential nutrients to not only fruits, veggies, and flowers but trees and shrubs, too.

I tested this on some conifers that were a little weather-worn using a hose attachment. Because of the higher concentration of nitrogen, in just a couple of weeks, I was excited to see all the browning foliage being replaced by new, bright green shoots. Check the latest price for Ferti-Lome Fish Emulsion Fertilizer.

How To Use:  Shake well before use, then mix 2 tablespoons per gallon monthly during the growing and blooming season.

Customer Reviews: Gardeners who tried this on trees, shrubs, and even their lawn are reporting being so pleased with the response they got. Such vibrant color and vigorous growth, even at the height of summer. Awarding this product 4.7 out of 5 stars.


  • Versatile for use on lawns, trees, and shrubs
  • Essential nutrients for flower, fruit, and veggie plants


  • May attract deer in rural areas 
  • Results may vary in poor soil 

2. GS Plant Foods Hydrolyzed Fish Fertilizer 2-3-1

GS Plant Foods Hydrolyzed Fish Fertilizer 2-3-1

I felt this one was a little on the pricey side until I realized how little you need for surprising results. I tested this hydrolyzed formula as a foliar spray on some new fruit tree saplings. Not one yellow leaf and they doubled in size in just one season.

I also tried this product on some peas and beans, resulting in the plants reaching over 6 ft tall plus a bumper crop of green veg. With the beans especially, the more I picked, the more they seemed to just keep coming. Find prices for GS Plant Foods Hydrolyzed Fish Fertilizer here.

The N-P-K ratio in this fertilizer is relatively low, meaning it is fine to use regularly without the worry of root or leaf burn, and can even be incorporated into your usual watering regimen.

Its application isn’t just limited to young trees and green veg, however. It has a multitude of uses from indoor plants, flowering perennials, vegetable gardens, and lawns, as well as trees and shrubs.

How To Use:  Houseplants – 1 tablespoon per gallon of water fed every 2-3 weeks. Outdoor plants – 2 oz per gallon of water. Apply until soil is saturated or as a foliar feed until leaves are wet.

Customer Reviews: Word-of-mouth has been the best advertiser for this product. Commercial users, families, and fellow gardeners are referring others to this for ailing plants and trees. Not to mention, abundant crops with very good value for money. 4.7 out of 5 stars.


  • Great value for money and multitude of fertilizing uses
  • Remarkable growth and vibrant color


  • Higher price point than others
  • May exhibit a strong odor 

3. Neptune’s Harvest Fish Fertilizer 2-4-1 

Neptune's Harvest Fish Fertilizer 2-4-1

Neptune’s Harvest contains macro and micronutrients plus trace elements with naturally occurring enzymes that stimulate healthy growth. It fed my plants while also improving the soil when used as a soil drench and foliar feed. I tested this on my tomatoes and squash using a hose attachment and I could actually see more vibrant foliage and fruit color from even the early days of feeding. View Neptune’s Harvest Fish Emulsion at Amazon.com

I must admit, I tend to use fish fertilizer for outdoor use as I’m conscious that most fish-based feeds are aromatic, to say the least! I was pleasantly surprised to find no strong odor with this option so it could feasibly be used for indoor plants, too. 

How To Use:  Indoors – Use 1 tablespoon per gallon of water every 1-2 weeks. Outdoors –  Use 1/8 Cup (1 fl. Oz.- 1:128) per gallon of water every 1-2 weeks. 

Customer Reviews: Rose enthusiasts are elated with their thriving plants that now look like show roses. Houseplant growers love the fast growth they’re seeing without the typical smell of fish fertilizers. 4.7 out of 5 stars.


  • Contains naturally occurring enzymes that stimulate growth
  • For use as a soil drench or foliar spray


  • Higher price point

4. Neptune’s Harvest Organic Hydrolized Fish & Seaweed Fertilizer 

Neptune's Harvest Organic Hydrolized Fish & Seaweed Fertilizer 

My final pick is another goodie from Neptune’s Harvest. This one contains seaweed as well as fish. It provides a vast range of nutrients to meet the needs of plants, shrubs, trees, and lawns.

When feeding your lawn, there’s no worry about wearing protective clothing or waiting to let your kids and pets play on it, because it’s organic. The hydrolyzed formulation means essential oils and proteins are left intact to benefit everything in your garden. Click here for Neptune’s Harvest Fish & Seaweed Fertilizer.

How To Use:  Indoors – Use 1 tablespoon per gallon of water every 1-2 weeks. Outdoors –  Use 1/8 Cup (1 fl. Oz.- 1:128) per gallon of water every 1-2 weeks.

Customer Reviews: Consumers love a fertilizer that pulls organic double-duty for the same price. Those that made the switch to organic didn’t regret that decision one bit after trying this. Many have been using it for years without fail and won’t go back to anything else. 4.7 / 5 stars. 


  • A mix of nutrients from both fish and kelp
  • Organic results without harmful chemicals


  • Overfeeding may cause plant burn
  • Smell may attract animals 

Which Plants Like Fish Emulsion Fertilizer ?

Switching to fish emulsion will provide you with versatility when it comes to your gardening and horticultural needs. First up, it will benefit houseplants, resulting in healthy and robust growth.

In addition, it will encourage an abundance of buds on outdoor ornamentals and, also, strong, healthy fruits and veggies. If that wasn’t enough, the nutrients can help deciduous trees and shrubs grow stronger and more tolerant to environmental stresses, while lawns will grow thick and vibrant in color.

The N-P-K ratio and secondary elements in fish fertilizer can’t be beaten for organic gardening, a practice that is gaining in momentum and popularity by the day. Just remember that recommended dosages must be followed to avoid over-fertilizing and plant burn.

How To Use Fish Fertilizer 

How you use this fertilizer depends on the application method of your chosen product. Powders and concentrates are diluted in water and applied directly to the soil or as a foliar spray. Use a watering can for small areas or a hose attachment for larger garden spaces for quick feeding.

Dry applications are worked into the soil or sprinkled around a plant’s base for a time-saving, slow-release option. Whichever one you choose, fertilizing can begin at the beginning of spring and continue until mid-autumn, then store it with no worries of spoilage. 

How Often Should You Fertilize With Fish Emulsion? 

Quick-action, liquid options generally need to be applied every 1-2 weeks to maintain a steady flow of nutrients to your plants and trees and achieve optimum results. Dry formulas, as slow-releasers, will typically need to be applied once every 1-2 months to achieve the same results.

While these are general recommendations, specific dosage instructions on the label should always be followed to avoid plant damage from overfeeding. 

Verdict: Best Fish Emulsion Fertilizer

Topping my leader board is the Ferti-Lome Fish Emulsion Fertilizer formula. This will help you to produce strong and healthy foliage and buds with plenty of vitality across all areas of your garden.

You should choose GS Plant Foods Hydrolyzed Fish Fertilizer if you need a foliar spray without the risk of burning the leaves of your plants. This fertilizer has a mild formula that means you can incorporate it into your usual watering regime.

Alternatively, if you are looking for a fish emulsion with less odor than the others and have intentions to use it indoors as well as outside, then choose Neptune’s Harvest hydrolyzed fish formula. This fertilizer has a strong, well-rounded blend of nutrients that will support your plants from every angle. No matter which one, it’s a choice toward fruitful success. 

FAQ’s Fertilizing With Fish Emulsions