As fish emulsion is most commonly used as a fertilizer, it is most readily found in stores that carry products for garden maintenance, such as Home Depot. It can also be purchased on eBay.
Fish emulsion is produced from the liquid remains of fish industrially processed for oil and fish meal. It is considered an organic fertilizer because it is naturally derived, and may be used in organic horticulture. It is available in most stores selling gardening products.
It is also possible to make one's own fish emulsion. Use any size of bucket with a lid, and fill it two-thirds full with alternating layers of fish scraps and brown plant matter, such as dead oak leaves. Top with water and seal the lid, then leave to steep for around one month. The resulting emulsion is concentrated and must be diluted before use.