Man-made fish are aquatic organisms whose existence or specific characteristics result from human intervention rather than solely natural processes. Humans influence fish species through various methods, such as altering genetic material, guiding reproduction, or combining different species, leading to distinct varieties not typically found in the wild.
Genetically Modified Varieties
One method of human intervention involves directly altering the genetic material of fish through biotechnology. This process, known as genetic engineering, inserts specific genes from one organism into another to introduce new traits. The AquAdvantage Salmon is an example of a fish developed through this technology.
The AquAdvantage Salmon is an Atlantic salmon (Salmo salar) that has been genetically modified to grow more rapidly. This accelerated growth is achieved by incorporating a growth hormone gene from the Chinook salmon (Oncorhynchus tshawytscha) along with a regulatory sequence, or promoter, from the ocean pout (Macrozoarces americanus). This genetic alteration allows the salmon to produce growth hormone year-round, enabling it to reach market size in about half the time of a conventional Atlantic salmon.
The U.S. Food and Drug Administration (FDA) approved the AquAdvantage Salmon in November 2015, marking it as the first genetically engineered animal cleared for human consumption. To minimize potential environmental impact, the salmon are raised in land-based containment facilities, such as those in Canada and Indiana. Strict measures are in place, including producing all-female, sterile populations, to prevent interbreeding with wild salmon.
Fish Developed Through Selective Breeding
Selective breeding is another method for creating distinct fish varieties. This method involves humans consciously choosing individuals with desirable traits to reproduce over many generations. The process does not involve direct genetic manipulation but rather guides the evolutionary trajectory of a species by emphasizing certain characteristics. Over time, this selection leads to new varieties significantly different from their wild ancestors.
Fancy goldfish originated from the common carp (Prussian or Gibel carp) over a thousand years ago in China. Breeders observed natural color mutations, particularly gold and red, and began to selectively breed these individuals. Through centuries of this practice, many fancy goldfish varieties emerged, exhibiting elaborate fins, unique eye types, and varied body forms like the Oranda, Ryukin, and Bubble Eye.
Koi, known for their vibrant colors and intricate patterns, also trace their lineage back to the common black carp in Japan. Japanese rice farmers in the early 1800s began to notice and selectively breed carp with naturally occurring color mutations. This cultivation led to the development of Koi varieties, each recognized for its specific color combinations and patterns.
Betta fish, or Siamese fighting fish, exemplify selective breeding for ornamental traits. Wild Bettas possess smaller fins and less vibrant coloration compared to their domesticated counterparts. Through generations of selective breeding, hobbyists have enhanced their finnage and colors, focusing on traits like fin shape (e.g., Halfmoon, Crowntail) and diverse color palettes.
Hybrid Species Created by Crossbreeding
Hybridization involves crossbreeding two different species or even genera to produce a new hybrid. These hybrid offspring inherit traits from both parent species or may display unique characteristics, such as increased vigor or hardiness. Such crosses are performed in controlled environments, as they may not occur naturally in the wild.
The Hybrid Striped Bass is an example of a fish created through crossbreeding for aquaculture. This hybrid results from the union of a striped bass (Morone saxatilis) and a white bass (Morone chrysops). These hybrids are valued in farming due to their faster growth rates and increased tolerance to varying water conditions compared to their parent species. Two common types of Hybrid Striped Bass are the Palmetto bass (female striped bass crossed with male white bass) and the Sunshine bass (female white bass crossed with male striped bass).
The Flowerhorn Cichlid is another hybrid, bred for its ornamental appearance. Originating in Southeast Asia, primarily Malaysia, Taiwan, and Thailand, in the late 1990s, Flowerhorn Cichlids are a mix of several Central and South American cichlid species. Their parentage includes species like the Red Devil Cichlid, Midas Cichlid, Trimac Cichlid, and the Blood Parrot Cichlid. These hybrids are recognized for their nuchal hump (a fatty growth on the forehead) and coloration, traits enhanced through breeding.