“Vermin: Animals that try to eat your nishikigoi”
http://www.fishchannel.com/fish-magazines/ponds-usa/2012/koi-glossary-words.aspx
[This entry in the glossary is funny, because every other koi-related term is Japanese. ‘Vermin’ is the only English word in the entire glossary.]
Very good - thanks for your reply !