Marine biotoxins are a diverse range of naturally occurring compounds with various groups of structurally related toxin families exhibiting very different solubilities and mechanisms of toxicity. The presence of toxins in a wide number of marine phytoplankton, which may be accumulated in filterfeeding bivalves and other Shellfish, can subsequently impact upon the health of the Shellfish consumer. To ensure consumer protection, the monitoring of many of these toxin classes is a statutory requirement. Biological assays, including the rat or mouse bioassay (MBA), have long been used for the determination of sample toxicity for many of the different toxin groups, providing either a quantitative or qualitative monitoring technique for Shellfish food safety.