The Benefits of Fish Fertilizer and How to Use it
Fish fertilizer is an excellent organic fertilizer you can purchase or make at home. Horticultural expert Lorin Nielsen shares how it's produced and how this amendment can give you fantastic produce!
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The idea of fish fertilizer may sound strange. How can fish provide a food source for my outdoor plants?
But it shouldn’t come as any surprise that like many other natural products, fish can be a great fertilizer. Chock-full of vitamins, amino acids, proteins and more, fish fertilizers are organic. They offer other micronutrients which standard NPK fertilizers lack.
Yes, they can have a fishy smell to them, but once diluted, the smell fades quickly. And your plants will love them. You’ll grow to love them too!
Interested? Let’s dive into the wonderful world of fish fertilizers and supplements.
What Is Fish Fertilizer?
Fish fertilizers take many different forms. They differ in how they are produced and what the end result looks like.
Fish Meal
Fish meal is a byproduct of the production of fish oils. This is produced by cooking and pressing fish, then drying and grinding the meat and bone.
While it’s not composted, this meal is often used as a soil amendment to improve soil health. Available in compressed cakes or a loose meal form, it is a fine, brownish material. It can be a grainy or powdery consistency, easily worked through your soil.
Fish Emulsion
What is fish emulsion fertilizer? There are two different variations.
Most commercial fish emulsion fertilizer begins with meal. The meal leftover from the oil extraction process gets put through a steam bath. This extracts proteins from the meal which condense into a container. The liquid is one form of fish emulsion fertilizer.
A second variation is produced in a more rudimentary fashion. Remnants from fisheries (such as the internal organs or heads of fish) are stockpiled. These are cooked down and strained to produce a fish emulsion fertilizer.
Fish emulsion fertilizer tends to smell like fish, and many people aren’t fond of the aroma. It can be thick, resembling molasses, or slightly thinned down. It is meant to be diluted in water before use.
Hydrolyzed Fish Fertilizer or Fish Hydrolysate
Hydrolyzed fish fertilizer has a similar end product to fish emulsion fertilizer. It’s liquid and may be thick, with a pungent fishy aroma. It’s produced in a different way than fish emulsion is, and can even be done at home.
Typically a batch of hydrolysate is made from whole fish or the remnants from fisheries. Internal organs, fish heads and tails, scales, meat, and bones are used. This material is ground into a paste. It is then fermented to break down the fish material into a liquid fertilizer.
DIY fish fertilizer uses a similar process of fermentation to break down the fish. It can take some time for fermentation to occur, and it’s pretty stinky while it’s happening! The remaining liquid is filled with fish amino acids, proteins, and more. These nutrients are easily absorbed by the plants and act as a good nutrition source.
Fish Waste
Finally, there is fish waste. This is a term used to refer to the waste products that fish themselves produce while alive. In an aquaponics system, fish live in a tank or pond system attached to a garden space. As the fish produce waste and it breaks down in the water, a pump will direct some of the water to the garden.
The garden acts as a filtration system for the water, removing any particulate in the water. Nutrients in the waste are absorbed by the soil, and any excess water is piped back to the tank. Much like animal manure, fish waste is a viable fertilizer source.
However, it’s only viable in an aquaponics system and is not commercially available on its own.
Fish Fertilizer Benefits
In bygone years, fish fertilizer was a common way to boost plant growth. But modern fish fertilizers work a bit differently from other organic fertilizers, with a long list of benefits.
Some, like fish meal, offer slow-release nutrition. The dried and granulated fish remnants still need to be composted down in the soil. Over time, meal improves soil health and provides nitrogen, phosphorous, and potassium. It also provides other minerals and vitamins your plants need, such as calcium or iron.
Both fish emulsion fertilizer and hydrolyzed fish fertilizer are liquids. The fish has been broken down into easier-to-absorb plant food. Once diluted in water, the liquids are commonly used as a foliar spray or in drip irrigation systems. They provide more rapid NPK feeding to your plants as well as other micronutrients.
If you like to go fishing, or you can get fish remnants from a local butcher or fishery, you might as well use them as fertilizer. Hydrolyzed fertilizer is easy to DIY, and can be cheap to do. You’re diverting waste from landfills while providing food for your plants. It’s a great eco-friendly solution.
Fish fertilizer benefits go further than just plant food, too. With fish hydrolysate, you’re also feeding the microbial population of your soil. These soil-dwelling microbes can help your plants take up nutrition better. They break down whatever your plant can’t digest into a form that they can.
Don’t just think of fish fertilizer or fish emulsion as good for plants. It’s good for the soil and for your eventual food harvest or flower production too. It helps reduce the waste dumped in landfills and allows you to recycle it into something useful.
How To Make Fish Fertilizer
It’s highly unlikely anyone will make fish meal or fish emulsion at home. But making a hydrolyzed fish fertilizer is much easier to do. You’ll need airtight containers, an abundance of fish, and some form of sugar. Either brown sugar or molasses mixed into sawdust can work for the sugar component.
The process is similar to bokashi composting. In this anaerobic process, bacteria break down the fish over a period of months, making it into a liquid fertilizer. After straining it to remove large pieces (which you can then re-process to break down further), dilute amounts of this in water to use as fertilizer.
Frequently Asked Questions
How often should I use fish fertilizer on my plants?
During the growing season, apply every two weeks. In extreme heat and cold, avoid applying fertilizers in general.
What plants do best with fish fertilizer?
Almost every plant can benefit, especially annual vegetables. The only outdoor plants that don’t appreciate it are those that aren’t fond of fertilizers to begin with.
What can I use instead of fish fertilizer?
There are so many organic fertilizer options out there. Seaweed fertilizers are also easy to make at home, or you can turn your garden weeds into a fertilizer tea. The options you choose will depend on what your garden needs.
Is fish fertilizer good for blooms?
It is! Fish fertilizer contains not only the basic macronutrients needed to support plant and soil health, but it also has tons of trace nutrients that promote better and longer blooms.
