Is Fish Fertilizer Good for Plants? You Might Be Surprised!


Are Fish Fertilizers really good for Plants?

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When it comes to fertilizing plants, I’ve realized that many people haven’t heard of using fish fertilizer, also referred to as fish emulsion on their plants. The few who have heard of people using it on plants don’t know if they should try it on their own plants. Does it have the right balance of phosphorus, nitrogen, and potassium? Is it just hype or is fish fertilizer good for plants?

Fish fertilizer is a great plant fertilizer, as well as a fantastic stand-in for traditional fertilizer. Fish fertilizer A.K.A. fish emulsion contains potassium, phosphorus, and nitrogen as well as sulfur, magnesium, and calcium, which plants crave and thrive on when given regularly.  

In this article, I’ll explain exactly what fish fertilizer is, what’s in fish fertilizer that makes it so beneficial to your plants and I’ll even include a list of the best fish fertilizer brands and products to buy for your own plants.

Let’s get started!

What Is Fish Fertilizer?

Fish fertilizer is more often referred to as fish emulsion. An emulsion is simply what happens when two unblendable liquids come together. What are those liquids? For fish fertilizer, they’re fish meal and fish oil.

Fish meal–which can also be spelled fishmeal–is ground-up fish parts that are deemed inedible, such as the offal and bones. (Offal is organ meat, by the way) It’s manufactured in one of two ways, in cakes or as a fine powder. Fish meal doesn’t cost a lot of money to make, so farmers like to use it.

Fish oil is a little easier to stomach, as it’s a commercially-produced and sold supplement. You might even have some fish oil in your kitchen cabinets right now.

The oil comes from oily fish tissue, including mackerel, swordfish, tuna, trout, or salmon. The omega-3 fatty acids found in fish oil can benefit those who don’t get enough omega-3s in their diet.

Okay, so those are the parts of fish fertilizer: bones and omega-3s. How does the fish become fertilizer? To emulsify a fish, manufacturers will take parts of the fish if that’s all that’s available, including its skin, scales, and bones. If they have the whole fish to use, that’s even better.

Similar to making fish meal, the fish gets ground down, but the result isn’t a powder. Instead, it’s a slurry, which is a combination of dense solids.

That slurry is the emulsion and thus the fish fertilizer. Before the process is complete though, the slurry undergoes straining so it’s free of solids.

Some manufacturers will include sulfuric acid in fish fertilizer so more microbes can grow within the fertilizer as well as to boost its acidity.

Should You Use Fish Fertilizer on Your Plants? What Are the Benefits?

Although its origins aren’t conventional, fish fertilizer is technically a fertilizer and completely appropriate to use on plants. Here are some of the amazing benefits of using fish fertilizer on your plants

Fish Fertilizer Can Provide Needed Nutrients for Your Plants

When using any fertilizer, it must have three key nutrients. These are potassium, nitrogen, and phosphorus, as I mentioned earlier.


Potassium allows for carbohydrates, nutrients, and water to travel through a plant’s tissue. The mineral also kickstarts the activation of enzymes for producing adenosine triphosphate or ATP as well as starch and protein.

Chlorophyll, which plants rely on for photosynthesizing and for their natural green coloring, exists in part due to nitrogen. Further, nitrogen allows proteins to stack and become amino acids, stabilizing a plant’s life.

With phosphorous, plants can send nutrients throughout their plant system, convert starches and sugars, photosynthesize, and transfer energy.

Fish fertilizer has these three basic plant nutrients in spades, but that’s not all. Fish fertilizer also contains sodium, chlorine, sulfur, magnesium, and calcium.

Here’s what each of these additional minerals found in fish fertilizer can do for your plants.


  • Sodium: When fed to indoor plants on occasion, sodium promotes chlorophyll synthesis and increases a plant’s metabolism.
  • Chlorine: In small doses, chlorine can keep plant leaves firm and help their stomata close and open. Stomata are plant pores that allow a plant to absorb or release gases like oxygen and carbon dioxide. Photosynthesis can also occur due to chlorine.
  • Sulfur: Plant proteins develop through sulfur, as can enzymes.
  • Magnesium: Each chlorophyll molecule throughout a plant’s tissue has a central core made of magnesium. Even still, supplementing your houseplant with more magnesium through fertilizer keeps their enzymes healthy and their growth steady.
  • Calcium: Although plants don’t have bones, calcium can still support them. This mineral keeps the cell walls structurally strong.

Fish Fertilizer is Organic

When buying fertilizer at a gardening supply store, some is organic and others not. Organic fertilizer uses bone meal, compost, or manure as the base, for example. Well, considering the source of fish fertilizer is fish, it’s completely organic too!

Fish Fertilizer Adds More Microbes to the Soil

Another benefit of fish fertilizer is how the soil processes it. Compared to a synthetic fertilizer which may release its nutrients quickly, fish fertilizer takes a while to break down. Fungi, earthworms, and bacteria within the soil have to digest the contents of the fish fertilizer first.

Once it happens, the nutrients within the fertilizer travel to the roots, where your plant sustains the fish fertilizer benefits. As a bit of a side perk, having more microbes in the soil keeps it healthy.

Fish Fertilizer Helps to Aerate the Soil

For example, microbes aerate the soil. Since they microbes are much more active and moving about, the soil gets shifted and loosened. Pockets of air form, allowing the plant within the pot to receive plentiful oxygen. The speed of root growth might increase, and the roots that form could be stronger than average, creating a very healthy foundation for plant life.

Using Fish Fertilizer Helps Prevent Fish Waste

The parts of a fish that get repurposed into fish fertilizer are the inedible parts. Meaning, they’re not going to end up on your dinner plate. What does happen to the fish waste is that it’s left to accumulate in large quantities, then it’s released into the ocean.

According to the EPA, this practice is incredibly detrimental in several ways.

If the fish waste was diseased, those diseases can spread to the living creatures in the ocean. Further, all that fish waste is a tasty snack to some creatures, not to mention it’s a free meal. Pouring fish waste into the ocean can allow for interocean species invasion. These non-native creatures break up the food chain and wreck the ecosystem in this part of the ocean.

Plus, dumping fish waste in large quantities can sometimes smother or bury alive the animals in the ocean that mainly dwell near or along the bottom of the ocean floor. The surviving animals in these contaminated areas often have less oxygen due to the dumping, which can cause these creatures to have to vacate parts of the ocean that have had large amounts of fish waste dumped into their ecosystem.

Each time you choose to use fish fertilizer for your plants, you help prevent these very unsettling problems from happening, at least a little bit.

Fish Fertilizer is Multipurpose

Besides its use as a plant fertilizer, fish emulsion is a great ingredient for a thriving compost pile. You can also rely on it when making a foliar spray. This means of applying liquid fertilizer on the leaves is supposed to encourage nutrient absorption through a plant’s epidermis or stomata. You might even use fish fertilizer as a soil drench to ward off infestations of pests.

Does Fish Fertilizer Leave Your Plants Smelling Bad?

Not necessarily. If you buy an non deodorized fertilizer, then yes, do prepare for a fishy stink that can make being around your garden less appealing. Deodorized fish fertilizer may have no smell or an artificial but pleasing scent.

Best Fish Fertilizer for Indoor & Outdoor Plants

Unless you’re a fisherman (or woman), then you probably don’t have a readily available source of fish. Here are a few tried & true fish fertilizer brands and products I’ve put together for you that can all be delivered courtesy of Amazon. I’ve added a few that I’ve tried and liked to help get you started.

Harris Organic Liquid Fish Fertilizer

If you’re growing an indoor or outdoor vegetables, Harris’ organic liquid fish fertilizer is what I recommend you use. They’ve been around since 1922 and understand that natural organic fertilizer is the best approach to boosting the health of the plants you plan on eating. Benefiting tomatoes and any other veggie you grow with the hopes of eating, Harris’ fish fertilizer is also usable on shrubs, lawns, fruit trees, as well as flower pots.

Bloom City Organic Wild Fish Fertilizer

This Alaskan salmon-based fish fertilizer from Bloom City is rich in omega-3s and amino acids. Food-grade and organic, Bloom City does mention their fertilizer reeks of fish, so that’s something you’ll have to consider if you choose Bloom City.

GS Plant Foods Organic Liquid Fish Fertilizer

If you have a yard as well as an indoor or outdoor garden, GS Plant Food’s fish fertilizer comes in gallon containers that will be sure to last you a while. Their natural fertilizer promises to increase yield size, strengthen the soil, and help your plants grow bigger. The included (all natural) nutrients and minerals are calcium, proteins, peptides, and of course, phosphorus, nitrogen, and potassium. Similar to Harris Organic liquid fertilizer, it’s aimed at indoor and outdoor use , so consider going this route if you are lucky enough to have a yard to care for.

Neptune’s Harvest Fish & Seaweed Fertilizer

Wait, seaweed? Yes, you can use seaweed as a fertilizer much the same way you do fish fertilizer, and Neptune’s Harvest has both ingredients in their liquid fertilizer. Intended for growing veggies, do know that you don’t get equal amounts of phosphorus, nitrogen, and potassium in this formula. That’s because it’s geared more toward blooming flowers rather then vegetables.

Fred Zimmer

I'm a lover of plants, animals, photography, & people, not necessarily in that order. Currently, I'm focused on photographing indoor plants & chachkies. I write & rewrite articles about creating an environment where indoor plants can thrive. I'm good at listening to music but bad at shopping to muzak.

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