It seems easy in the animal kingdom to name a young animal, like a cub or a foal. Things get a bit more complicated with fish when each part of their development seems to have a different name. Things can even get more confusing when certain species of fish have even more names according to the fish’s development.
A baby fish is called a hatchling or larva, a fry, and a fingerling depending on which state of juvenile development it has reached. A salmon’s growth extends from fingerling to a parr, a smolt, and post-smolt. Baby eels are called by the quaint name of elvers.
The general names for immature fish follow the larva, fry, and hatchling designation except for a few examples of the more unusual or larger species of marine vertebrates. If you were wondering what the correct name for the baby fishes you encounter, we have made an easy list for you to find out the proper names that baby fish are called.
The Stages of Juvenile Fish Growth
Larvae or hatchlings
When fish larvae first emerge from their fertilized egg after they have hatched, they are hatchlings. They have yet to develop the necessary features to feed themselves and are still sustained by part of the egg yolk hanging below them for about two to three days. Their mouthparts have not yet developed on the hatchlings to feed themselves and so they can not provide them themselves with nutrition for their external environment.
The larval fish look very different from their parent fish because they have larval adaptations to keep them alive at this early stage of their development. Their axial spines have just begun to develop, and they still have an Embryonic median finfold, which will disappear to the end of the larval stage. In the late stage of the larval process, the fish begins to feed itself from picoplankton, zooplankton, or a mixture of the two.
The larval stage can vary in duration from carp, which lasts one or two days, to sardines at one to two weeks and eels that have a larval phase of several months.
The Fry Stage
It takes about 7-10 days on average for young fish to grow from a hatchling into a fry. Once the young fish have begun to feed themselves, they are called fry. They begin to develop secondary characteristics and start to look like a miniature version of the adult of their fish species.
The yolk has wholly been used up, and the young fish’s swim bladder has become operational to allow its proper movement. Usually, the fry is between 1-2 centimeters long and may swim freely and search for plankton to eat.
The Fingerling Stage
In approximately 30 to 60 days, depending on the fish breed, the small fry will develop into what is called a fingerling. At this stage of development, the little fish can extend its fin, and they have started developing scales throughout their body. At this stage, the fish will be about 10-15 centimeters or roughly the length of an adult finger (where their name originally arose.)
The Juvenile Stage
The juvenile stage begins when the transformation from larval to juvenile is completed. The features that mark a young fish are that all the fin rays are developed, and the scale growth is well underway. This juvenile stage is complete when the juvenile reaches sexual maturity and begin to interact with other adult fish of its species.
The Stages of Growth of a Salmon
Sac Fry or Alevin
This stage of a salmon’s development is when they are still dependent on their yolk sacs for nourishment. After two to six months, the tiny alevin hatch from the eggs and are hidden in the gravel of streams and rivers until their yolk phase is over.
When the alevin has consumed all their yolk, they rise from the protection of the gravel and begin to feed themselves on plankton.
The Parr Stage
Towards the end of summer, the fry develops into parr. The parrs feed on small invertebrates and camouflage themselves from predators with stripes and spots. They remain in the parr stage for up to three years.
The young parr loses their camouflage colors and becomes a smolt and begins the physical changes to shift from freshwater to saltwater. They begin to grow the silvery scales to confuse their ocean predators and adjust their body chemistry to cope with the increased salination levels of the ocean.
When the smolt is about 15-20 centimeters long, the swim out of the rivers and into the ocean, they begin their first year as post-smolt and form schools with other post-smolts to find food in the deeper ocean. Once they have reached sexual maturity, they reach adulthood.
Other Names For Baby Fish According to Species
Eels are an unusual ray-finned fish from the family Anguilliformes, and they have a somewhat different developmental process to your standard larvae, fry, and hatchlings. The eel begins its life as a flat, transparent larva called leptocephali, which is Greek for ‘thin head.’
They drift about the sea, feeding on small particles that float on the surface called ‘marine snow’ until they grow into what is called glass eels. Glass eels are no bigger than a pinkie and look more like see-through earthworms than the adult eel.
Once they are mature enough, they are called elvers. Most elvers remain in the sea, but some elvers are forced to climb across terrain and obstacles like dam walls and waterfalls to mate.
The young of sharks are called pups, and various shark species either lay eggs or give birth to developed live young. When a shark lays an egg, it is called a mermaid’s purse and made to blend in with the ocean plant life.
A newborn whale is called a calf and is born tail first after a gestation period of about 11 to 16 months. The newborn calf is usually already a quarter to a third of its mother’s body size at birth.
The manta ray gives birth to live young after 11-13 months of gestation, which is also called pups like shark offspring. The growth of the young manta is then divided into the yearling stage, the juvenile non-reproducing stage, and the mature adult (8-10 years.)
The sunfish is an unusual-looking fish that boasts the most significant reproductive output of any other fish. With mature females releasing 300 million eggs at one time, you would think that the ocean would be full of them. But most of these eggs enter the water column and become food for other creatures in the sea.
When sunfish larvae hatch, they are 2mm long and remain in small schools for protection until they develop into fry. From fry, they grow rapidly to their mature size.
So now that you know your fingerlings from your fry, you will never be at a loss when trying to explain baby fish when you are in conversation. Whether its elvers calves or smolts, you can be confident that you won’t have to use the words’ baby fish ever again. Unless, of course, its baby shark dooo dooo de do de dooo!