The fiddler crab [above] is a very easy pet to keep. They will not grow bigger than a 4cm wide. They can be kept with other reptiles such as the fire-bellied toad or the fire bellied newt or a fighting fish [the pets above I have together ].for the crabs you can give them cooked meat or veggies ,also they will eat the algae in the aquarium .you're aquarium should have some water [about 15cm max] then you need a rock for them to sit on and a hiding place .there are also other types of crabs that you can keep like the red claw crab they are a bit larger and more aggressive but you can keep them together just keep them the same size[be careful the red claws will attack you're hand and it will hurt].
