As a man-made hybrid, the flowerhorn cichlid is a tropical freshwater fish that is believed to have been selectively bred from a number of other natural species, including the blood parrot, oscar, red devil, Texas cichlid, and more. There are many different sub-varieties with differences in color, markings, and the size and shape of the lumpy protrusion at the top of the head. As it is not a natural creation, there is substantial controversy surrounding the scientifically-engineered flowerhorn cichlid, both physical and philosophical. Despite its poor general health and the increased likelihood of disease, this fish is able to tolerate a wide range of conditions. It is an extremely aggressive carnivore and has caused localized devastation and extinction in areas where it has been released into the wild.
These fish are medium-sized, carnivorous creatures, measuring around 12 inches (30 centimeters) in captivity, with specimens reportedly reaching double this size when released into the wild. As voracious middle- to bottom-feeders, flowerhorn cichlid specimens will eat any type of carnivorous flakes, pellets, frozen, fresh, or live foodstuffs. Given their higher risk of poor general health and susceptibility to disease, it is advisable for keepers to provide vitamin-enriched foods on a regular basis to promote good health.
Flowerhorn cichlids are extremely aggressive and should be kept alone. They will attack any other cichlids and attempt to eat any other tank mates. It is even common for opposite sex pairs to fight, causing extensive damage to one another, or fighting to the death. It is, therefore, often necessary to separate the pair with a strong partition in the tank until the aggression passes. Keepers should also be aware that these fish will often attempt to bite the keeper if given the opportunity.
The aggression can be so extreme that flowerhorns often damage themselves alone in the tank, particularly the head and mouth as they ram or attack tank decorations or the side of the tank head first. Because of this, it is necessary to use only smooth decorations with no corners or sharp protrusions. The tank must be made of sturdy, reinforced materials, as these fish have been known to break flimsy tanks.
As with other hybrid species, there is a great deal of controversy surrounding the flowerhorn cichlid. Poor general health and a significantly increased risk of certain diseases, such as tumors, have fueled the debate regarding the ethics and morality of deliberately creating new species. Another cause for concern is the continued breeding of that species when detrimental characteristics are known to occur very frequently, such as the flowerhorn cichlid's ability to severely devastate an entire ecosystem.
Despite the higher risk of disease or ill health, the flowerhorn cichlid is very hardy and survive in a wide variety of conditions, meaning many of the discarded fish survive. This creates another issue surrounding the creation of the flowerhorn cichlid and other human-engineered species is the serious danger they may pose if released into the wild. As an alien species released into the environment, the flowerhorn cichlid or any other alien species, has the potential to devastate an established ecosystem, causing irrevocable damage, wiping out native flora, and fauna. This disruption has already happened in parts of Malaysia and Singapore, where unscrupulous flowerhorn breeders have discarded unwanted stock into local bodies of water because the fish either not attractive enough, have smaller head humps, or other deformities.
The released fish breed and multiply very quickly, eating or simply killing many native specimens. With no constraints, confinement, or limits to their food supply, these fish thrive and grow much larger than they do in a tank environment. Their aggression and voracious appetite mean that they devour or kill almost anything in their path. The vice president of the Malaysian Anglers Association stated that the situation is extremely serious, as many native species are under immediate threat, with some species already having suffered localized extinction.