Making Fermented Fish Emulsion For The Garden

A person might wonder why on earth someone would even want to make fermented fish emulsion for their gardens. There is actually more than one answer to the question. First, this yields a liquid fertilizer that is exceptionally good for garden plants. It is balanced, so it isn’t too high in nitrogen, potassium or phosphorus. It also contains micro-nutrients that many soils might be lacking, which helps the garden plants grow strong and vigorously. Second, it is a powerful deer and rabbit deterrent. The stuff stinks. Once it is diluted and applied to the plants, within a couple of hours, people no longer smell the stench, but it remains. Deer and rabbits have s very sensitive sense of smell and they do not like the odor. Who can blame them? So how do you make the stuff?

To start with, you need some fish. It can be trash fish that were caught, fish innards or even scraps of fish from the local fish market. Many fish markets are all too happy to give away all the scraps you want. The fish can also be either freshwater fish or ocean fish. To make three gallons of the fermented fish emulsion, you’ll want about two to three pounds of fish. When it is finished, the emulsion will be concentrated, so it is diluted before feeding it to the plants. Dilution is about one cup of the emulsion to a gallon of water, applied every two weeks.

What Else You Need

You will want a container capable of holding three gallons. A plastic bucket works well, but it does need a lid to keep the flies out while it is fermenting. You are out to make a superior fertilizer, not to have a maggot hatchery.

You’ll also want two to four pounds of dry plant material. This could be grass clippings, leaves, pine needles, hay or straw. In a pinch, even shredded paper can be used. The point is that all of these are high in carbon content and carbon is important for the proper breakdown of material during composting. The emulsion is actually nothing more than a very rapid composting process, using fish instead of the normal ingredients people put in compost. Another difference is that normal compost utilizes aerobic bacteria to break down the material. Aerobic bacteria are those that need oxygen in order to live. The emulsion uses anaerobic bacteria, the kind that don’t use oxygen to survive. This is the kind that makes a stink, which isn’t found in normal composting, if it is done right.

Additionally, you need a catalyst to get the whole process going, fast. There are probably several things you could use for a catalyst, but one of the best I’ve found has been a cupful of molasses.

Emulsion process

Some people like to use raw fish and fish parts, chopped up and put in the container. My preference is to boil the fish in about a gallon of water for a half hour to an hour. This begins the breakdown process before the bacteria even do their thing. The fish does need to cool down to room temperature before proceeding, but you can use the water the fish was boiled in, adding this to the container when the fluid is cooled. If you are using raw fish, add a gallon of water to the container once the fish has been added.

Next, add the dry plant matter and pour the molasses over the top. Stir up the mess in the container or cap it and shake it up, then add enough water so the bucket is full to within about two inches from the top. This head space is important because as the fermentation takes place, carbon dioxide is released and this can create substantial pressure.

Loosely cap the container. You want to allow the carbon dioxide to escape while preventing flies from getting inside and laying eggs. If the cap is too tight, the container might burst. If it is too loose, you might end up with a bunch of maggots. Note that maggots don’t harm the emulsion and it can still be used for the plants, but maggots produce flies and most people aren’t great on the idea of having additional flies around the home or garden. For this reason, the fermenting fish should be kept somewhere away from the house. Also note that there are buckets with fermentation locks on them that are specifically for making this sort of thing.

Stir the mixture every day for four days to two weeks. You may need to hold your nose when you do this. At the end of the four days to two weeks, the emulsion is ready for use. Simply pour a cupful in a used, empty plastic milk container, fill the jug up with water and feed it to the fruits, herbs and vegetables at the rate of about one cup per plant, every two weeks.

This might seem like a lot of effort, dealing with something that gets exceptionally stinky, but once you see the difference this makes to the harvest coming out of the garden, you’ll be glad that you made the emulsion. Whether you want giant tomatoes, huge heads of cabbage, a tremendous harvest of peppers or mega pumpkins, this stuff is great for the plants. It is totally organic and the only real expense is usually the molasses. The side benefit is that rabbits and deer usually steer clear of the garden and go looking for succulent plants to nibble on in places that don’t smell as bad. Sometimes it is great that we don’t smell aromas as well as wildlife can.

Note: If you wonder if the fermented fish emulsion really works, take a look at the picture. I took this picture of a single day’s harvest off of three eggplants, all of which were being fed the emulsion. Eggplants are known for being heavy feeders. Also keep in mind that we live in the Rocky Mountains of Montana, which isn’t well known for growing semi-tropical fruits like eggplants.


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    This seems to be very costly because I will have to buy fish. Are there any cheap alternative?

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    Rex Trulove Post author

    @vinaya, I usually catch my own, but you might check with stores that sell fish. Very often, they have the parts left over that people won’t eat and will give away those parts…the guts, heads and what have you. If they sell fish filets, you might even get more than that. If that isn’t possible, check with restaurants. Again, it is likely that you will find some that will give you the parts that they can’t sell. Friends who fish is another resource you might use. Even fish that is too old to be eaten can be used, so there should be several ways you can get a hold of the fish.

    A person *could* use frogs or the like, I suppose, though I’ve never tried it.

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