FishReproduction
Fish Reproduction
In terms of underwater species, there is generally less information about their reproductive systems than many other terrestrial animals due to the fact that they are more difficult to research and observe. Although there may be less information, common fish reproduction mating systems have been observed that range from monogamous and polygamous systems all the way to hermaphroditism. Oftentimes, it is difficult to label mating patterns of fish and many fish species fall within a continuum of mating systems dependent upon the current environmental conditions. Within these reproductive systems, subcategories of behavior can be readily distinguished between fish species. Though monogamy is rarely broken down farther, polygamy can be divided into subcategories of polygyny, polyandry, and polygyandry, which can also be further explained by unique patterns of fish behavior. Like the other fish reproductive systems, hermaphroditism can also be broken down further into subgroups that include sequential hermaphroditism and simultaneous hermaphroditism as well as protogyny and protandry. Sexual reproduction can also be characterized by active mating, where both sexes are directly involved in the physical process of reproduction and leads to internal fertilization within an organism, or passive mating, which can be characterized by broadcast spawning - also known as mass spawning or synchronous spawning - where an organism releases their eggs or sperm into the water column to be later fertilized externally by a member of the opposite sex.
Monogamy
Monogamy is the practice where males and females have prolonged pair bonds. Monogamy usually establishes that an equal amount of males and females will contribute gametes to the offspring population. Monogamous relationships in fish species are usually practiced when individuals of the opposite sex are generally hard to find or environmental conditions find monogamous relationships to be more favorable to the species. In fish, it is very rare to find long term pair bonding with the exception of butterflyfish. More frequently, fish participate in sequential monogamy where the monogamous pair is only extended over one mating period instead of long-term. Parental care from monogamous pairs is more often seen in freshwater fish, but rarely in reef fish. Though many fish do not choose to participate in monogamous sexual relationships, the few species that do tend to be extremely territorial. Monogamous freshwater fish include substrate spawners, mouthbrooders, and bubblenesters, including the cichlidae, osteoglossidae, heteropneustidae, channidae, and bagridae fish families. An example of a monogamous saltwater fish would be the anglerfish, which lives at depths much deeper than most coral reefs.