There are reports of hybridisation between the crucian and domestic or feral goldfish,[1] which has been verified by production of viable hybrids in laboratory conditions.[10] Although the hybrids thus produced were sterile or nearly so, genetic contamination of the native population has been raised as a concern;[10] even if the hybrids cannot continue to propagate, the F1 hybrids exhibit hybrid vigour or heterosis, being much more adept at finding food and evading predators than either of their parents, which has been proposed to constitute a possible threat to the native crucian carp population.[10]