One-time spawning - eggs are laid all at once, in one go, in a short period of time (whitefish, salmon, roach, perch, and many other fish). This phenomenon, developed during the long period of formation of the species, is caused by the short fattening period for the young that have hatched and the impossibility for the following portions to survive. Many tropical fish spawn within an hour. All eggs of such fish intended to be hatched in a given season mature immediately and are completely hatched.
It is not uncommon for the same species to spawn simultaneously in one body of water and in another to spawn in portions. For example, the bream in the Aral Sea has batch spawning, while in northern water bodies (Lake Onega, etc.) it spawns simultaneously.
Tags: one-time spawning