Schreckstoff, German for “scary stuff,” is a chemical compound, glycosaminoglycan chondroitin, that some fish species release when they are injured.  This “take-one -for-the-team” signal lets their conspecifics know that there is danger in the area.  But more than just an alarm signal, Schreckstoff also serves as an immune response for the injured individual, warding off parasites and pathogens such as molds, trematodes, and solar radiation. 

This piranha may look scary, but when it’s scared, it will release Schreckstoff


 Schreckstoff is utilized by fish superorder, Ostariophysi, such as minnows, catfishes, and characiformes (including piranha and tetras), and has also been documented in other species, such as salmonids. (fishionary.fisheries.org/schreckstoff)

For more information, please visit: The Fisheries Blog‘s post on “Scary Stuff!“