Freshwater crayfish predominantly walk and, thus, require surface area to inhabit, necessitating a certain amount of area to grow and reproduce. Most Australian freshwater crayfish swim by flicking their tail rapidly forward ventrally and, hence, propel backwards. This is a defensive escape method if deemed threatened, a technique developed by these animals to survive effectively in aquatic environments. Most crayfish are also excellent escape artists able to undergo seemingly impossible feats to leave their water, venturing for the perceived better environment. Keeping crayfish in where they are required is the task of both the aquaculturist and aquariam keeper.
High stocking densities for culturing crayfish, depending on continual water quality, may be in the order of 250 grams per square metre. This would equate to one 250-gram crayfish, which is very large and resembling more the lobster, or 25 10-gram juveniles. Crayfish are sometimes aggressive, territorial and cannibalistic, particularly the yabby, Cherax destructor, as the name implies. If conditions get too crowded, water quality deteriorates and/or food becomes exhausted, freshwater crayfish will kill and eat each other and/or attempt to leave their environment. In this scenario, the main result to be aware of is stress to the stock.