The species of fish.
Since the fish bred in aquariums generations, there was a clear tendency to choose the most colorful animals for breeding. So many of the most popular tropical aquarium fish kept today, have more vivid coloration than their wild forms. Modern methods helped to selekcioniruut varieties from original wild forms taken from natural habitat, to new forms, genetically-modified breed, and available for every aquarist.
The science of genetics, explores the possibility that species characteristics pass from one generation to the next. The characteristics of all living organisms, including fish, are contained in genes, which are rod-shaped structures called chromosomes, present in the nucleus of every living cell in the body. Mutations, or sudden changes in genetic structure can occur, and sometimes result in a change in the appearance of fish, such as coloration, body shape and fins. When there is a mutation in certain cells eggs or milk, the change is transmitted to the next generation. Most mutations are only carried out minor changes that can be improved by selective breeding over many generations. In some cases, there may be a mutation that creates a radical change. Yellow Gold angelfish (Pterophyllum sp. var.), resulted from mutations that caused poteryannogo of pigment that normally masks the yellow tint. Mutations can also be harmful, it stands out, in very many groups of fish, where you might get a few deformed individuals.
Genetic modification of fish.
Selection and crossbreeding.
Photo: After the successful varieties, such as this Black Variegated Delta Guppy ( Poecilia reticulata ), it was found that the best parents are selected for each pairing of the future, to ensure that the strain is maintained and improved.
Under normal circumstances, individuals of separate species, breed with individuals of the same species. Sometimes it is possible, to provoke individuals from two different species to mate, creating offspring with new characteristics. This method to create new types of aquarium fish controversial because these fish have never existed in the wild. Crossbreeding is widely used to create various forms of popular viviparous, including the famous Black Mollies, gourami hybrids the most colorful and exciting with the Parrot cichlid.