crayfish species should, however, not lead their keepers to the
assumption that regular water maintenance is unnecessary. On the
contrary, good filtration and regular water changes are a must in
every crayfish tank.
Crayfish have a very hard exoskeleton, and thus cannot grow
continuously. When they shed their old skin (or molt), they
experience a growth leap. A crayfish is never fully grown but will
continue to shed its skin and grow immediately after every molt.
Of course, they molt more frequently and thus grow faster while
still young, and their relative size and weight gain per molt is larger
than for older crays. Very old crayfish molt, but they do not grow
significantly at all. Instead, they just renew their old skin that is
sometimes overgrown with algae and other micro-organisms.
Every molt is life-threatening for a crayfish. Often, an unsuccessful
molt marks the end of a crayfish’s life. If the old skin gets too
tight, it is shed in order to make room for a new, larger one. For
this purpose, the old exoskeleton gets softer and more elastic as
hormones trigger metabolic processes that remove calcium from it.
After that, the crayfish can slip out of its old skin.
As crayfish inhabit very different biotopes, it is hard to make a
general statement about their diet. Usually, crayfish are omnivores,
which means they eat food of vegetable and animal origin.
Most species will eat anything organic, in fact. The choice of
foodstuffs they eat in nature well demonstrates their variability and
adaptability regarding food: rotting wood, detritus, algae, fungi,
bacterial layers, aquatic plants, dead tree leaves, terrestrial plants,
fruit, seeds, insects, crustaceans, worms, mollusks, fish, and other
Keeping freshwater crabs is by no means easy. They are intelligent
invertebrates with highly developed sensory organs, and they need
special environments. As crabs have quite individual temperaments,
their keeper needs to observe them closely to be able to meet their
needs. Crabs are highly interesting crustaceans to keep and can fill an
aquaterrarium with life.
They are quite susceptible to changing habitat conditions and stress,
though, so they need a lot of room and good hiding places under and
above the waterline. Many species require a section of dry land in the
tank, as their life strategy is amphibian. Unlike other crustaceans, the
size of crabs is indicated by their carapace diameter, not body length.
A dedicated aquaterrarium for dwarf land crabs can be decorated
with mosses, rocks, and driftwood. The air humidity should be as
high as possible.
Thai red crab (Pseudosesarma moeschi).
Vampire crab (Geosesarma sp.).