**3. Sources of** *Salmonella* **contamination in fish and fishery products**

Aquatic environments are the major reservoirs of *Salmonella*. Therefore, fishery products have been recognized as a major carrier of food-borne pathogens (Kamat et al., 2005; Upadhyay et al., 2010).

Pathogenic bacteria associated with fish and fishery product can be categorised into three general groups: (1) bacteria (indigenous bacteria) that belong to the natural microora of sh (*Clostridium botulinum*, pathogenic *Vibrio* spp., *Aeromonas hydrophila*); (2) enteric bacteria (nonindigenous bacteria) that are present due to fecal contamination (*Salmonella* spp., *Shigella* spp., pathogenic *Escherichia coli*, *Staphylococcus aureus*); and (3) bacterial contamination during processing, storage or preparation for consumption (*Bacillus cereus*, *Listeria monocytogenes*, *Staphylococcus aureus*, *Clostridium perfringens*, *Salmonella* spp.) (Lyhs 2009).

Information from literature indicates that fresh fish, fish meal, oysters, farmed and imported frozen shrimp and froglegs can carry *Salmonella* sp., particularly if they are caught in areas contaminated with faecal pollution (prior to harvest and during harvest) or processed, packed, stored, distributed under unsanitary conditions and consumed raw or slightly cooked (Kumar et al., 2003; Kamat et al., 2005, Mol et al., 2010; Norhana et al., 2010).

There are some pathways of contamination of aquaculture systems with *Salmonella.*

#### **Non-point water run-off**

During rainfall events, increased run off of organic matter into ponds may occur and can contaminate the aquaculture system.

#### **Animals (domestic animals, frogs, rodents, birds, insects, reptiles, etc.)**

A variety of animal waste has been shown to be potential sources of *Salmonella*. Animal waste can be introduced directly through bird droppings or frogs living in ponds or indirectly through runoff.
