Angelfish

Naming

The most commonly kept species in the aquarium is ''Pterophyllum scalare''. Most of the individuals the aquarium trade are captive-bred. Sometimes, ''Pterophyllum altum'' is available. Captive bred ''P. altum'' is available but occasionally. ''Pterophyllum leopoldi'' is the hardest to find in the trade.

Reproduction

''P. scalare'' is relatively in the aquarium, although one of the results of generations of inbreeding is that many breeds have almost completely lost their rearing instincts resulting in the tendency of the parents to eat their young. In addition, it is very difficult to accurately identify the gender of any individual until they are nearly ready to breed.

Angelfish pairs form long-term relationships where each individual will protect the other from threats and potential suitors. Upon the death or removal of one of the mated pair, breeders have experienced both the total refusal of the remaining mate to pair up with any other angelfish and successful breeding with subsequent mates.

Depending upon aquarium conditions, ''P. scalare'' reaches sexual maturity at the age of six to twelve months or more. In situations where the eggs are removed from the aquarium immediately after spawning, the pair is capable of spawning every seven to ten days. Around the age of approximately three years, spawning frequency will decrease and eventually cease.

When the pair is ready to spawn, they will choose an appropriate medium upon which to lay the eggs and spend one to two days picking off detritus and algae from the surface. This medium may be a broad-leaf plant in the aquarium, a flat surface such as a piece of slate placed vertically in the aquarium, a length of pipe, or even the glass sides of the aquarium. The female will deposit a line of eggs on the spawning substrate, followed by the male who will fertilize the eggs. This process will repeat itself until there are a total of 100 to more than 1,200 eggs, depending on the size and health of the female fish. As both parents care for the offspring throughout development, the pair will take turns maintaining a high rate of water circulation around the eggs by swimming very close to the eggs and fanning the eggs with their pectoral fins. In a few days, the eggs hatch and the fry remain attached to the spawning substrate. During this period, the fry will not eat and will survive by consuming the remains of their yolk sacs. At one week, the fry will detach and become free-swimming. Successful parents will keep close watch on the eggs until they become free-swimming. At the free-swimming stage, the fry can be fed newly-hatched brine shrimp or microworms. It is generally accepted that brine shrimp are the superior choice for fast growth rates of fry.

''P. altum'' is notably difficult to breed in an aquarium environment.

Evolution

The freshwater angelfish was first talked about by Lichtenstein in 1824. Being scientifically named ''Pterophyllum scalare'' , the meaning of Pterophyllum is "winged leaf".

It was not until the late 1920s to early 1930s that the angelfish was bred in captivity in the United States.

In 1963 another species of Pterophyllum were discovered, P. leopoldi, this species was described by Gosse. In the beginning they were first described under another name, with P. leopoldi becoming the valid scientific name. Prior to that a species by the name of Pterophyllum altum had been discovered in 1906 by Pellegrin. There may still be undiscovered species in the Amazon River. New species of fish are discovered with increasing frequency, and, like P. scalare and leopoldi, the differences may be subtle. Scientific notations describe the P. leopoldi as having 29–35 scales in a lateral row and straight predorsal contour. Whereas, the P. scalare is described as having 35–45 scales in a lateral row and a notched predorsal contour. The leopoldi show the same coloration as scalare. Leopoldi can show a faint stripe between the eye stripe and the first complete body stripe and a third incomplete body stripe between the two main body stripes that extends three-fourths the length of the body. Whereas, the scalare's body does not show the stripe between the eye stipe and first complete body stripe at all, and the third stripe between the two main body stripes rarely extends downward more than a half inch, if even present. The leopoldi fry develop three to eight body stripes, with all but one to five fading away as they mature, whereas scalare only have two in true wild form throughout life.

Angelfish were bred in captivity for some 30 years prior to leopoldi being described; possibly longer outside the United States.