Planted Tank VIP
Join Date: Jul 2002
Location: Victoria,British Columbia, Canada
Well, depending on the species.. anywhere from 4" to 14". Its hard to say, some Macrobrachium's can be agggressive, while others can be bold, but not active hunters.
Just watch them as they grow and you'll be a better judge of how they're going to behave. There are hundreds of species out there so its hard to say for certain what you have.