Juvenile fish

"fish (fry)" redirects here. For the food product consisting of fried fish, see fish fry.
This young Chinook salmon, with scales and working fins, is a fingerling but known as parr specific to salmon

Juvenile fish go through various stages between birth and adulthood. They start as eggs which hatch into larvae. The larvae are not able to feed themselves, and carry a yolk-sac which provides their nutrition. Before the yolk-sac completely disappears, the tiny fish must become capable of feeding themselves. When they have developed to the point where they are capable of feeding themselves, the fish are called fry. When, in addition, they have developed scales and working fins, the transition to a juvenile fish is complete and it is called a fingerling. Fingerlings are typically about the size of fingers. The juvenile stage lasts until the fish is fully grown, sexually mature and interacting with other adult fish.

Growth stages

Juvenile fish bypass for a hydroelectric dam

Ichthyoplankton (planktonic or drifting fish) are the eggs and larvae of fish. They are usually found in the sunlit zone of the water column, less than 200 metres deep, sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals.[1][2]

According to Kendall et al. 1984[2][3] there are three main developmental stages of fish:

This article is about the juvenile stage.

Juvenile salmon

See also: Salmon run

Fry and fingerling are terms that can be applied to juvenile fish of most species. But some groups of fishes have juvenile development stages particular to the group. This section details the stages and the particular names used for juvenile salmon.

Protection from predators

Juvenile fish need protection from predators. Juvenile species, as with small species in general, can achieve some safety in numbers by schooling together.[8] Juvenile coastal fish are drawn to turbid shallow waters and to mangrove structures, where they have better protection from predators.[9][10] As the fish grow, their foraging ability increases and their vulnerability to predators decreases, and they tend to shift from mangroves to mudflats.[11] In the open sea juvenile species often aggregate around floating objects such as jellyfish and Sargassum seaweed. This can significantly increase their survival rates.[12][13]

As food


Juvenile fish are marketed as food.

See also


  1. What are Ichthyoplankton? Southwest Fisheries Science Center, NOAA. Modified 3 September 2007. Retrieved 22 July 2011.
  2. 1 2 Moser HG and Watson W (2006) "Ichthyoplankton" Pages 269–319. In: Allen LG, Pondella DJ and Horn MH, Ecology of marine fishes: California and adjacent waters University of California Press. ISBN 978-0-520-24653-9.
  3. Kendall Jr AW, Ahlstrom EH and Moser HG (1984) "Early life history stages of fishes and their characters" American Society of Ichthyologists and Herpetologists, Special publication 1: 11–22.
  4. 1 2 Guo Z, Xie Y, Zhang X, Wang Y, Zhang D and Sugiyama S (2008) Review of fishery information and data collection systems in China Page 38. FAO Fisheries and Aquaculture, Circular 1029. FAO, Rome. ISBN 978-92-5-105979-1.
  5. 1 2 Bley 1988
  6. 1 2 Lindberg 2011
  7. 1 2 Atlantic Salmon Trust 2011
  8. Bone Q and Moore RH (2008) Biology of Fishes pp. 418–422, Taylor & Francis Group. ISBN 978-0-415-37562-7
  9. Blaber SJM and Blaber TG (2006) "Factors affecting the distribution of juvenile estuarine and inshore fish" Journal of Fish Biology, 17 (2): 143–162. doi:10.1111/j.1095-8649.1980.tb02749.x
  10. Boehlert GW and Mundy BC (1988) "Roles of behavioral and physical factors in larval and juvenile fish recruitment to estuarine nursery areas" American Fisheries Society Symposium, 3 (5): 1–67.
  11. Laegdsgaard P and Johnson C (2000) "Why do juvenile fish utilise mangrove habitats?" Journal of Experimental Marine Biology and Ecology, 257: 229–253.
  12. Hunter, JR and Mitchell CT (1966) "Association of fishes with flotsam in the offshore waters of Central America". US Fishery Bulletin, 66: 13-29.
  13. Kingsford MJ (1993) "Biotic and abiotic structure in the pelagic environment: Importance to small fishes" Bulletin of Marine Science, 53(2):393-415.
  14. Basque food: Angulas Retrieved 14 February 2012.


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