Photo credit: World Fish Center

Review: Abdel Rahman El Gamal (Founder of the website)

Fermented fish has been a traditional and highly popular food in Bangladesh. Fermentation as a method of preservation still enjoys popularity in many developing countries owing to its simplicity and low cost of processing. The Fermentation of fish takes place as a result of the action of autolytic enzymes and microorganisms being naturally present in the guts and intestine of fish. The drop of the pH in the fermented fish muscles below 4.5 serves as a barrier to many spoilage microbes. Fermentation is one of commonly used fish preserving methods especially in tropical countries as it  makes fish species popular during their bulk harvest and is highly justified when applied to underutilized species.

The inserted pictures are related to the production of Fermented fish (Hedol Shukti) at the bank of Surma River, Sylhet, Bangladesh where people are known to be very fond of fermented fish product.

Some fish species suit more the fermentation whether due to their abundance or due to body characteristics. The preferred species for fermentation include several types of small silver barbs like olive barb (Puntius sarana), Jat Punti (Puntius sophore), tit punti (Puntius ticto), etc.

Fish fermentation begins with sun-drying whereas traditionally, fish are not washed before sun-drying. Very often, scales are not removed and gill remains intact with the fish. Fish drying requires 4-5 days while moisture content comes down to approximately 20-25%. Afterwards, dried fish can be immediately used for the fermentation process which is completed in clay pottery.

A small amount of water (3-5%) is sprinkled with salt granules over the dried fish in order to just soften it prior fermentation. Dried fish are symmetrically arranged in layers and packed tightly in the container as far as possible giving no chance of air to ensure the anaerobic condition. The opening of the container is sealed with banana leaf and polyethylene paper, and then after the mouth is completely closed and sealed with mud.

The clay container is buried underground keeping only the mouth above the ground level. The container is kept in this condition for 3 to 4 months before containers taken out of the ground and kept at room temperature for marketing of the product.