Ostracitoxin

When under stress, a boxfish (family Ostraciidae) will release the Ostracitoxin toxin (see: http://www.sciencemag.org/cgi/content/abstract/146/3641/244). It is an ichthyotoxic, hemolytic, nonprotein (which is apparently unusual, although similar to Tetrodotoxin in this way) poison in the mucous secretions of their skin. This is a heat-stable and nondialyzable; that is foamed in aqueous solutions and is toxic to various biological systems. It is unique among known fish poisons. It is toxic to other boxfish as well and looks like red tide and sea cucumber toxins in general properties. Although it is not recommended, it is a growing fancy to keep boxfish in a home aquarium. Members of the family Ostraciidae secrete an ichthyotoxic mucus from their skin when stressed or disturbed.

The boxfish must be alive to synthesize its bodily chemicals into the toxin, therefore it cannot release its toxin after it dies. It may, however, have residual toxin if it were in the process of releasing toxin when it died.

References

Ostracitoxin: Donald A. Thomson - An Ichthyotoxic Stress Secretion of the Boxfish, Ostracion lentiginosus - Department of Zoology, University of Arizona, Tucson - http://www.sciencemag.org/cgi/content/abstract/146/3641/244