12.3.1  Environmental conditions that can contaminate fish

Fish are generally considered clean and fresh, but several environmental factors can make fish unfit for consumption. The factors relate to the food of the fish itself – the fish is what it eats – and to the cleanliness/safety of the water body. Fish can also be contaminated by poor handling at any stage from being caught to being eaten.

Water bodies can be contaminated by:

• Industrial chemical wastes which may contain heavy metals.
• Farm chemical drainage containing pesticides which may bioaccumulate; for example, DDT accumulates in fish tissues.
• Domestic and commercial wastes, drainage and runoff, which may be contaminated with faeces or other pollutants.