Cardinalfish come in many different shapes and colours, generally they are well suited for aquaria.
Cardinalfish have a large mouth and a big appetite, take this into account with feeding the other fish. These fish typically live off of Artemia, Mysis and krill. In the aquarium they will eat anything they can.
They will sometimes eat small shrimps and fish, so do be aware of this, but it is not normally a problem.
It is possible to keep several species together, if space allows. Some species will form small shoals. They are normally peaceful towards other fish, but will sometimes fight among themselves if there isn't sufficient space or food.
Many species are nocturnal and will therefore often seek a hiding place during the day. This can be between stones, SPS corals and, in some cases, in an anemone and between spines of Sea urchins.
Cardinalfish are a good choice if ones wishes to attempt to start a breeding tank.