vinegar eel

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A small nematode worm (Turbatrix aceti) that feeds on the organisms causing fermentation in vinegar and may be present in unpasteurized vinegar.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun minute eelworm that feeds on organisms that cause fermentation in e.g. vinegar