Fish
Barramundi
Lates calcarifer · also called Asian sea bass, giant perch
A barramundi is a big silver fish that lives its life in two directions. It spawns in the salt water of a river mouth, grows up years later in fresh water far upstream, and moves between the two on the wet-season tides. And it lives its life as two sexes: nearly every barramundi is born male, breeds as a male, then turns female — so the metre-long trophy fish is always an old female that used to be a young male.
Overview
The barramundi, Lates calcarifer, is a large ambush predator of the tropical Indo-Pacific, from the Persian Gulf to Australia, in coastal seas, estuaries, mangrove creeks, tidal rivers, and floodplain billabongs. It is a carnivore that engulfs fish, prawns, and crabs whole with a sudden gulp, and it has reflective eyes that glow red in a torch beam for hunting in murky water. The name is an Aboriginal word from Queensland meaning “large-scaled river fish”.
Two directions, two sexes
Barramundi are catadromous — they spawn in salt water and grow in fresh, the reverse of salmon — with adults running down to the coast to breed around the wet-season new and full moons and the young pushing far upstream to mature. And they are protandrous hermaphrodites: male first (from ~3–5 years), then female (from ~6–7 years), so big barramundi are almost all female. A large female can release several million eggs in one spawning.
Status
Least Concern and stable — widespread, highly fecund, fast-growing, and heavily farmed worldwide, which supplies most of the market. Wild stocks are managed with size and bag limits; the main concerns are dams and weirs blocking the migration, loss of wetland nurseries, and fishing pressure on the large old females.
Barramundi: common questions
Is a barramundi a bass or a perch?
Neither, despite being sold as Asian sea bass and formerly called giant perch. Barramundi is Lates calcarifer, a member of the family Latidae, the lates perches, which is related to the true perches only distantly. It is a large, silver, deep-bodied predatory fish of the Indo-Pacific, and the various market names, barramundi, Asian sea bass, giant perch, and in the aquarium trade the Australian sea perch, all refer to the same species. The barramundi name won out commercially because it is distinctive and because the fish is strongly associated with Australia.
Do all barramundi really change sex?
Nearly all of them, and always in the same direction, from male to female. Barramundi are protandrous hermaphrodites. A fish matures as a functional male at around 3 to 5 years and roughly 55 to 65 centimetres, spawns as a male for one or more seasons, and then its reproductive tissue reorganises and it becomes a functional female, usually by about 6 or 7 years and 80 to 90 centimetres. The practical result is that small and medium barramundi are mostly male and large barramundi are almost all female, and a trophy metre-plus barramundi is a female that may have started out as a male a decade earlier. A small number of fish appear to develop directly as females, but they are the exception.
Why do barramundi need both fresh and salt water?
Barramundi have a catadromous life cycle, the reverse of a salmon's. Spawning only works in salt or near-salt water, because barramundi eggs and newly hatched larvae need the salinity of an estuary or coastal sea to float and develop properly, so mature adults migrate downstream to river mouths to breed, typically on the big tides around the wet-season new and full moons. The tiny larvae then drift and swim into sheltered coastal swamps and, as juveniles, push upstream into freshwater rivers, billabongs, and floodplain lagoons where food is abundant and large predators are fewer, and they grow there for several years before heading back to the coast to spawn. Dams and weirs that block this movement can cut a river's barramundi off from breeding.
Is farmed barramundi a good choice to eat?
Barramundi is often recommended as one of the more sustainable farmed fish. It grows quickly, converts feed efficiently, and can be raised in well-managed recirculating tank systems that limit pollution and escape, and several barramundi farms in Australia, the United States, and elsewhere hold sustainability certifications. As with any farmed fish, the picture depends on the specific operation, particularly whether it uses open net pens in coastal waters, which carry the usual risks of waste, disease, and escapes, or closed land-based systems, and on how much wild-caught fish goes into the feed. Wild-caught barramundi from well-managed Australian fisheries is also generally considered a responsible choice.