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Spawning Cycle and Egg Production of Zebrafish, Brachydanio rerio, in the Laboratory
Robert C. Eaton and Roger D. Farley
Vol. 1974, No. 1 (Mar. 28, 1974), pp. 195-204
Stable URL: http://www.jstor.org/stable/1443023
Page Count: 10
You can always find the topics here!Topics: Female animals, Eggs, Ova, Egg production, Public aquariums, Clutch size, Freshwater fishes, Fish feeding, Embryology, Fish
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Single pairs of zebrafish, Brachydanio rerio, 12 months old, spawned at an interval of 1.9 days when the male and female were left continuously together. Three months later the spawning interval had increased to 2.7 days, suggesting that age is a factor in determining the spawning cycle. Hard water had no effect on spawning cycle in these experiments, nor did grouping the fish with three males for each female. An experiment was done in which prolongation of the spawning cycle was enforced by separating the male from the female for random intervals of 2-9 days. In 93% of the trials spawning occurred on the morning following reintroduction of the male after a 2-day separation. Similar results were obtained upon reintroduction of the male after 3-9 days of separation. The greatest number of eggs per day can be obtained by leaving the pair continuously together. In two experiments in which this was done the mean number of eggs produced per day per pair was 23.1 and 60.4. In the experiment where male and female were separated for 2-9 days, and then spawning was allowed to occur, egg production varied from 45 eggs per day per pair with 2 days of separation to 10 eggs per day per pair with 9 days separation. Evidence was obtained that egg development is triggered by interaction with the male. Eggs usually could not be stripped from the female without the male having been present. Introduction of the male for 7 hours at the end of one day enabled eggs to be stripped from the female the next morning. The precise stimulus for egg development was not determined, but it is suggested that it may be the chasing of the female by the male, behavior which goes on almost continuously when the two are together.