I've read with much interest from the internet how folks prepare homemade fish emulsion and swear by its effectiveness. There are so many articles saying how simple the process is in making fish emulsion. I suspect though that many of these how-to articles just parrot each other.
There is little material thus far, however, by way of photos and/or videos that illustrate the processes involved in this so-called simple procedure - as of this writing, anyway. So this article will illustrate, by pictures, just that.
Simple and easy - yes - but a bit messy and stinky. You will not believe how bad the stink can be. And for many, that may be an understatement because the basic raw material for fish emulsion is well, raw fish scraps (as shown below) which will be decomposed.
Sources of Raw Fish Wastes or Scraps
You will likely be able to get fish scraps or wastes in places where fish is cleaned prior selling or consumption. The fish section of the wet market will usually have traders removing fish parts like intestines, gills, liver, gall bladder, heart, fins, tail, scales and even bones. Typically, these are thrown away and so you could just ask them for free.
That's how we get fish scraps for free. Many traders in the wet market are just happy to get rid of their refuse from the fish cleaning. We're able to get a kilo or so by just asking. Of course the fish scraps include everything and you just can't become picky and select a few parts. I bring along a plastic container with a lid on it. Plastic bags won't do because of the risk of them bursting open.
Making Your Own Fish Emulsion from Fish Scraps
The procedures outlined below will yield roughly 2 liters of concentrated fish emulsion from 2 kilograms of fish scraps. Because of fish scraps volume, it will take 1 month for it to sufficiently decompose and for you to extract the fish emulsion. Your mileage may vary. Obviously, a smaller amount of fish scraps will yield a smaller amount of fish emulsion and will take lesser time.
The pulp that will be left behind after extracting and collecting the fish emulsion is not wasted. It may be used as a good starter mix for the next batch of fish emulsion, because of its state of decomposition. It may also be used to feed a compost pile that can later be applied and mixed into your garden soil.
Do NOT use the extracted fish emulsion directly on your garden plants. Instead, dilute to apply the fish emulsion as fertilizer.
1. Raw Fish Scraps - 2 kilograms
2. Molasses - 1 cup
3. Sawdust - 2 lbs.
4. 5-Gallon Plastic Bucket with Cover
5. Window Screen, 18" x 18" - 1 pc.
6. Garden Hand Rake or Spatula
1. Pour an inch-high layer of sawdust at the bottom of a 5-gallon bucket. This is the component in the mixture that absorbs extra nitrogen expelled by the decomposing fish. While others choose a variety of "browns" to be added like dried leaves, grass clippings, etc., I only put sawdust for consistency and to keep the entire process simple.
2. Pour all the fish scraps in the bucket. If the fish scrap has water, pour that in as well.
3. Put 2 tablespoons of molasses into the bucket. Molasses feeds the microbes that eventually decompose the fish parts. The sweet sugary smell of molasses does NOT remove the offensive odor of rotting fish, but simply masks it.
4. Mix the fish scraps, sawdust and molasses thoroughly with a garden hand rake or spatula. The reddish brown color below comes from the sawdust. It may be a bit heavy to mix all together because much of the fish scraps is still semi-solid.
6. Be sure the layer of sawdust is spread all around. If the sawdust quickly absorbs the mixture water and becomes wet, continue adding additional layers until the topmost layer of sawdust appears dry. The layer of sawdust will minimize and contain much of the offensive odor of rotting fish inside the bucket.
7. Cover the bucket with the window screen piece. Ensure the piece will sufficiently cover the bucket's opening and will have a couple of inches extra beyond the bucket's rim. The window screen prevents adult flies from getting inside the bucket. If adult flies are allowed to get inside the bucket, you'll have a problem with maggots.
8. Replace the bucket's cover and twist to secure the window screen in place. The window screen between the bucket and cover creates a space gap for air. It is NOT advisable to seal the cover because gases are formed during decomposition and need to escape.
Optionally, add a heavy weight on top of the bucket cover to weigh it down. This will prevent the accidental bumping off the bucket's cover. The weight will also discourage pets and animals from knocking it off.
9. Avoid opening the bucket anytime during the day for the next two weeks. Flies will almost immediately swarm towards the open bucket. If you need to open the bucket, do this at night.
The photo below of 3 flies on the bucket cover and window screen shows how smelly the contents have become. This photo was taken during the first week at daytime.
10. For the next four weeks, open the bucket every other day to mix and aerate the contents. The aeration discourages the buildup of anaerobic bacteria that contributes largely to the bad smell.
11. Continue adding 2 tablespoons of molasses as needed to help control the odor and aid in the decomposition of the fish scraps. Note that fish bones, heads, fins and tail will take longer to decompose.
In the first week, the stench will be horrible. Try to do the mixing at night when there are no flies. If there is wind, turn your back to where the wind is coming from so you won't smell most of the wafting odor. In the second week, the odor will smell like that of fish sauce that's common to Thai and some Asian cooking.
By the third and fourth week, much of the contents would liquefy because of decomposition. Because of that, it becomes easier to mix the contents. The odor will be less offensive, but still bad, nonetheless. The mixture will also be a bit darker because of the added molasses.
After four weeks or roughly a month, you'll be ready to extract and collect the fish emulsion.