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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== 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.〔(What are Ichthyoplankton? ) Southwest Fisheries Science Center, NOAA. Modified 3 September 2007. Retrieved 22 July 2011.〕〔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.〕 According to Kendall et al. 1984〔〔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.〕 there are three main developmental stages of fish: * Egg stage: Spawning to hatching. This stage is used instead of using an embryonic stage because there are aspects, such as those to do with the egg envelope, that are not just embryonic aspects. * Larval stage: From hatching till all fin rays are present and the growth of fish scales has started (squamation). A key event is when the notochord associated with the tail fin on the ventral side of the spinal cord develops and becomes flexible. A transitional stage, the yolk-sac larval stage, lasts from hatching to the absorption of the yolk-sac. * Juvenile stage: Starts when the transformation or metamorphosis from larva to juvenile is complete, that is, when the larva develops the features of a juvenile fish. These features are that all the fin rays are present and that scale growth is under way. The stage completes when the juvenile becomes adult, that is, when it becomes sexually mature or starts interacting with other adults. This article is about the juvenile stage. * Fry – refers to a recently hatched fish that has reached the stage where its yolk-sac has almost disappeared and its swim bladder is operational to the point where the fish can actively feed for itself.〔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.〕 * Fingerling – refers to a fish that has reached the stage where the fins can be extended and where scales have started developing throughout the body.〔 In this stage, the fish is typically about the size of a finger. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Juvenile fish」の詳細全文を読む スポンサード リンク
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