Freshwater crabs occur is several places around Australia and we have some in the streams and lakes here in the north. This little fellow is probably in the genus Holthusiana. It was found in a temporary pond during the wet season.
Holthusiana sp. Appears to be a small female. it has moutled at least once and does not seem to bother the fish. It feeds on plant material and flake fish food.
Each stream and lake up this way seems to have a variety of shrimp of many species in several different families. Many are quite colourful like the one below. It breeds in the community tank with plenty of fish present. There is abundant plant life that must hide the immature shrimps.
An unidentified freshwater shrimp.
Riffle Shrimp, Atyidae
These shrimp live in the fast-flowing portions of rainforest streams where they can be found amongst rocks and debris.
This is a Riffle Shrimp, Australatya striolata
These shrimp feed by gathering plant material and detritus off rocks and plants using brush-like setae on the tips of the claws of the first and second pairs of legs.
They are fairly easy to keep in the tank. This species likes fast-flowing water and positions itself in the stream of the return flow from the filter.
Setae on the front legs used to collect small food items.
Thanks to Keith Martin for suggestions.