Australian native fishes
            Many Australian fishes are rare or endangered through habitat alteration or the introduction of alien species, especially the Mosquito fish and European Carp.
I have had two species as aquarium pets for about 5 years. These are the Murray Cod  (Maccullochella peeli) and the Silver Perch  (Bidyanus bidyanus). Both are endangered species. They are raised by aquarists for the pet trade and by aquaculturists for stocking of dams, lakes and rivers. Until greed gives way to responsibility however and proper attention is given to restoration of habitat and elimination of mosquito fish and carp, the future for them is not certain.
General:  These two species come from the Murray-Darling drainage system and so are temperate species which prefer water temperatures around  15-30 ^oC  (ca 60-85^oF).  Being "cold-blooded" they eat a lot less food than do the normal run of pets such as mammals and birds. Growth rate and size are determined by the size of the tank, number of fish and amount of food supplied. Being rather territorial it is best not to keep two to four together of the Perch (one or a small school say 10 specimens is better), the Cod is best kept as a solitary fish.

Food:    Live food is preferred. The Silver Perch is omnivorous and will eat vegetation and small animals. When small (ca 1cm) they like live brine shrimp, black worms and small meal-worms. In a tank with a lot of waterplants and invertebrates living in the plants, Silver Perch can survive for a long time without interference from the owner.
    The Cod also prefers live food but will also accept chopped beef heart, liver or chicken hearts. The 30 cm specimen kept at my work site is tame enough to be fed by hand and will take whole chicken hearts.

Murray Cod (Maccullochella peeli)
 
 

    Murray Cod are perhaps the least interesting fish to keep, at least while small. They are shy and secretive and prefer to lie under some shelter, eg log, stone, filter equipment, waiting for food to swim by. They are more active at night but quickly resort to their hiding spots when the light is turned on. Large specimens are very impressive despite their passive behaviour. Murray Cod are the largest Australian freshwater fishes and in large, slow moving rivers can reach weights of 100 or more kilograms (ca 220 lb). Given plenty of food and a large aquarium they can grow to 30cms (1 foot) long in about 15 months. My own specimen has grown very slowly and has reached 18 cms in five years ( 1 cm when purchased).
 

Silver Perch (Bidyanus bidyanus)
 
 

    Silver Perch are more active than Murray Cod and will swim around the tank in daylight hours. I acquired two small specimens and they grew quite well from ca 1 cm long to about 10cm in three years. At that time one of them, possibly more aggressive, acquired an advantage in growth over the other and harried it for for food and space. Eventually the second fish became so stressed that it died. That is why it is better to have 10 or more specimens in a very large tank or just a single specimen. The surviving fish is now 20 cm long.