Fish and seaweed are often used together as fertilizer, and indeed, they’re somewhat similar.
They both provide broad-spectrum nutrition – not too much of anything, but a little of almost everything.
Where seaweed wins is in its natural plant growth regulators that help plants deal with various stressors.
But using fish as fertilizer does beat liquid seaweed in one way – it’s nitrogen content, and with many fish fertilizers, the phosphorus content.
Benefits Of Liquid Fish Fertilizer
Nitrogen and Phosphorus are two important elements that are often deficient when our soils aren’t yet up to par chemically and biologically:
- Nitrogen. Is the building block of proteins in plants, and ultimately in our bodies. We don’t need all that much nitrogen in the garden, but we do need a quality source, and that’s where liquid fish fertilizer comes in.
- Phosphorus. This element is important not just for root growth (as is the common myth), but it’s central to photosynthesis and building carbohydrates, and it’s involved with transporting almost every other mineral throughout the plant.
Plus, if you get a quality fish product, you’ll be getting oils, proteins, and enzymes that feed microbes and soil animals – that’s why I think of it as true whole food nutrition.
As with seaweed, I generally prefer a liquid form of fish fertilizer. Although fish meal definitely brings in some nutrition, some of the benefits are lost during its processing.
How To Make Fish Fertilizer
Get some fish and grind it up in a blender or food processor. If it’s a bony fish, you’ll need a solid machine.
Add enough water to cover the mixture and then process some more until it’s all blended up nicely.
There you go – you have a basic liquid fish fertilizer.
Now, you could use it right away by mixing it with 10 parts water and watering plants.
But to get more benefit, you can ferment it further so the nutrients will be more available for plants.
For that, I use 1 teaspoon of EM per cup of fish-water mixture, a 1:50 ratio.
If you don’t have that around, other kinds of probiotics will help.
Then, add 1 teaspoon of sugar per cup of fish-water to give the microbes an energy source.
Put the whole mixture into a container with a lid or towel over the top, but don’t tighten the lid because there will be gases produced that could cause the container to explode.
After a month, the smell will have decreased in intensity, which means the fish has been consumed by the microbes and your fish fertilizer is extra special and ready to go.
Finding A Quality Liquid Fish Fertilizer
There are so many fish fertilizer brands out there, it’s hard to keep track of them.
I recommend a fish hydrolysate fertilizer instead of a fish emulsion fertilizer:
- A liquid fish emulsion has had most of the fats and proteins removed for other uses. It’s cooked at high temperature, which destroys vitamins and enzymes. Also, chlorinated city water is generally used, so the end product is often high in chlorine. An example is the (unfortunately popular) ‘Alaska Fish Fertilizer’ made by chemical company Lilly Miller, which comes from the polluted Gulf of Mexico – not Alaska.
- A hydrolyzed fish fertilizer retains the fats, proteins, and enzymes because it’s processed at a cool temperature. A good hydrolysate will have this done before all of the bones, oils, etc. have been removed, when the fish are still fresh. Hydrolysates don’t smell nearly as bad as emulsions, which tend to use rotting fish, and they’re usually filtered better so they don’t clog equipment as much as emulsions.
I don’t mean to imply that a fish emulsion is useless – it’s still a worthwhile fertilizer. But put it this way – people who switch from an emulsion to a hydrolysate are often going to be happy, while people who move in the other direction are not, i.e. the difference is noticeable.
It’s like freshly-picked vegetables vs vegetables from a can.
A good hydrolysate is usually $20-$25/quart. I’ve seen a few at $10-$15/quart, but they’re usually using fish from polluted rivers (like the Mississippi) or lakes (like the Great Lakes) or they’re using farmed fish, or they’re creating a liquid fish emulsion fertilizer and then adding enzymes back in after so they can call the product ‘hydrolyzed,’ but still, many of the beneficial components of the fish will have been destroyed or denatured during the processing.
I prefer ocean fish from unpolluted waters. Organic Gem is a good one.
And Neptune’s Harvest is the one I settled on because I like everything they’re doing:
- With many fish, when they’re processed for food, most of the fish is wasted. Neptune’s Harvest is taking that waste and making use of it rather than dumping it back out at sea. Others are catching fish just to make fertilizer, which doesn’t sit quite as well with me.
- They’re fishing off the northeastern seaboard of the U.S. and they’re doing so very sustainably. It’s true that some parts of the world are overfished and some fish are overfished, but that area is being substantially underfished, not overfished.
- The fish come from the deep, cold, mineral-rich waters of the North Atlantic ocean, not from polluted areas near the shore or rivers or lakes, or from the Gulf of Mexico.
- They’re using many different species of fish, which conceivably makes for a more well-rounded fertilizer, although I suspect that’s less important.
As with most organic liquid fish fertilizers, they’re using a touch of phosphoric acid to drop the pH, because otherwise, the microbes in the product can get so active that the container might explode.
Phosphoric acid is the same stuff they use in Coca-Cola and it’s not great for us to be consuming, but in the garden, it’s VERY useful. This little amount is allowed in organics (indeed this product is OMRI-Listed), and I would strongly prefer to have it in there than not.
How To Use Fish Fertilizer
Shake well before each use because sometimes there’s a thick part that separates out.
Once you’ve mixed with water, use it the same day.
Since I also use sea minerals fertilizer, I alternate them every other month (eg. fish in March, sea minerals in April, fish in May, etc.). I use seaweed every month along with them.
In my garden, per 1000 square feet, I end up using 1/2 cup of liquid fish fertilizer, 4 times per year.
That works out to nearly 1/2 quart per 1000 square feet per year.
If I wasn’t using sea minerals, I’d spray it 8 months of year, which would be 1 quart per 1000 square feet per year.
If you want to spray it weekly, use 1/8 cup (2 Tbsp) per 1000 square feet instead.
The dilution rate can be between 1:50 and 1:100. I go with 1:50, which is a gallon of water for every 5 Tbsp of fish. I just use a hose-end sprayer set to spray 5 Tbsp per gallon.
Here are their suggested application rates:
- House Plants: Use 1 tablespoon per gallon of water every 1-2 weeks.
- Outdoors: Use 2 Tbsp per gallon of water every 1-2 weeks.
- Lawns: Use 1 gallon for 8000 sq ft every month.
- Seeds: Use 1 teaspoon per cup of water for soaking seeds.
- They suggest applying until the soil is saturated or as a foliar feed until the leaves are wet.
They recommend 3 gallons of product per acre, 4 times per year. That works out to about 1 quart per 1000 square feet per year.
You Can Get It Here
In summary, this liquid fish fertilizer:
- Provides many benefits, but is especially known for providing nitrogen and phosphorus that promote rapid plant growth, as well as the complete fats and proteins that microorganisms need.
- Is a hydrolysate, processed with enzymes at cool temperatures in order to retain all of the beneficial components.
- Is organic, OMRI-Listed, and not even too smelly.
- I ship in the U.S. only. I ship 7 days a week.
- In the continental U.S., shipping is $15.
- All of my products have a 1 year 100% money-back guarantee.
- If you have a question about a product, leave it in the comment section below I'll try to respond within a few hours.
- Dry fertilizers and compost tea brewers ship separately so they will arrive on their own maybe a day or 2 apart from my other products.
- I send a percentage of every order to Thrive For Good and other similar organizations. They're working mostly in Africa to help communities grow organic, medicinal food for themselves, and then use the surplus food to generate income for themselves as well as feeding the orphans in their communities.