yes they can, apparently a new employee had recieved this fish from someone who brought him in, im guessing outgrew ther tank, and put him in their 300g indoor goldfish pond, that same day the employee quits for whatever reason and never tells anyone what they got and where he went, so everymorning for like 3 weeks, they kept finding half huge goldfish and goldfish disapearing, eventually they dig through the pond and find this guy chillen in therehiding in the sand and rocks