Pterophyllum

Pterophyllum is a small genus of freshwater fish from the family Cichlidae known to most aquarists as "Angelfish". All Pterophyllum species originate from the Amazon River basin in tropical South America. The three species of Pterophyllum are unusually shaped for cichlids being greatly laterally compressed, with round bodies and elongated triangular-shaped dorsal and anal fins. This body shape allows them to hide among roots and plants, often on a vertical surface. Naturally occurring angelfish are frequently striped longitudinally, colouration which provides additional camouflage. Angelfish are ambush predators and prey on small fish and macroinvertebrates. All Pterophyllum species form monogamous pairs. Eggs are generally laid on a submerged log or a flattened leaf. As is the case for other cichlids, brood care is highly developed.

P. altum
Pterophyllum altum, (common name: Altum Angelfish or Orinoco Angelfish) occurs strictly in the Orinoco River Basin and the Upper Rio Negro watershed in Southern Venezuela, Southeastern Colombia and extreme Northern Brazil.[1] Its natural color is also silver but with three brownish/red vertical stripes and red striping patterns into the fins. The species may show red spotting when mature and when aroused exhibits a black operculum spot. Characteristic of this species is an acute incision or notch above the nares. All true (pure) specimens show this trait, whereas commercial hybrids product of crosses to Pterophyllum scalare, that are occasionally performed by breeders to sell them as "Orinoco Altum", will most likely not show this trait or show it to a much lesser degree. The true wildcaught Orinoco Altum is among the most challenging among tropical fish to breed in captivity. The species is the largest of the genus and specimens exceeding 50 cm in height (from tip of dorsal to tip of anal fin) have been reported in the wild; in aquariums, specimens are known to have grown to +40 cm. Altum Angels are more frequently found in the well oxygenated, extremely soft waters of Upper and Middle Orinoco tributaries shed from the Guyana Shield Highlands, preferring a pH range between 4.5 to 5.8. These are very transparent blackwaters with almost nil conductivity. Temperature range in these waters is between 78°F (26°C) and 84°F (29°C). They are also found in the Atabapo River and Inirida River floodplain, down the Casiquiare and Guainía floodplain where the Rio Negro is born, before entering Brazilian territory. Unlike P. scalare(mentioned above) which prefer to spawn on plants, P. altum prefers to spawn on submerged roots and tree branches. This species is recommended for intermediate to advanced aquarists due to the detailed maintenance it requires for proper health.

P. leopoldi
Formerly known as Pterophyllum dumerilli. The Pterophyllum leopoldi is a river dwelling angelfish species that originates from rivers in the Amazon River basin along the Solimões River, Amazon River, and Rupununi River.[2] Rarely available in the hobby, this fish can be discerned from Pterophyllum scalare in that P. leopoldi has a more horizontally elongated body than does P. scalare, and the black band which goes through the fish's eye does not sweep backwards towards the dorsal fin (as seen in P. scalare), but rather goes straight over the head and joins up on the other side. Some researchers believe that P. leopoldi is a synonom for the juvenile form of P. scalare.[citation needed]

P. scalare
Pterophyllum scalare, (common name: Angel or Freshwater Angelfish) is the most common species of Pterophyllum held in captivity. It is also the most widely spread species in the wild, and can be found in Peru, Colombia, the Amapá River in Brazil, also along the Ucayali River, Solimões and Amazon rivers, in Oyapock River in French Guiana and the Essequibo River in Guyana.[3]

Angelfish in the fishkeeping hobby
Angelfish are one of the most commonly kept freshwater aquarium fish, as well as the most commonly kept cichlid. They are prized for their unique shape, color and behavior. Many hobbyists consider angelfish to be a relatively intelligent fish, able to recognize their owners.

Care
Angelfish are kept in a warm aquarium, ideally around 80°F (27°C). They will do best if fed a mixture of flake, frozen and live food. Care should be taken to not overfeed, they will continue to eat even what they do not need. This will lead to a bulidup of fats resulting in inactivity and early death. Angelfish will do best if kept in an acidic environment, pH should be below 7.5. Although most aquarium-bred angelfish can survive in a wide range of pHs, wild-caught angelfish will need water with a pH of at least 6.5. Even though angelfish are a member of the cichlid family they are generally peaceful, however; the general rule "big fish eat little fish" applies. Other aggressive fish should not be kept with angelfish because their flowing fins are vulnerable to fin nipping! Some smaller more aggressive fish may even nip at the fins of these fish.

Breeding
P. scalare is relatively easy to breed 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, some breeders have experienced a total refusal of the other mate to pair up with any other angelfish; others have had more success with subsequent mates. Both parents care for the young.
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 up to 1200+ eggs, depending on the size and health of the female fish. 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 frozen och fresh (i.e. alive) brine shrimp (Artemia spp.).
P. altum is notably difficult to breed in an aquarium environment.

Strains of Angelfish
Most strains of angelfish available in the fishkeeping hobby are the result of many decades of selective breeding. For the most part, the original crosses of wild angelfish were not recorded and confusion between the various species of Pterophyllum, especially P. scalare and P. leopoldi, is common. This makes the origins of "Domestic angelfish" unclear. Domestic strains are most likely a collection of genes resulting from more than one species of wild angelfish combined with the selection of mutations in domesticated lines over the last 60 or more years. The result of this is a domestic angelfish that is a true hybrid with little more than a superficial resemblance to wild Pterophyllum species. It would be inaccurate to say that they accurately represent any species of wild angelfish, although they most resemble P. scalare and are frequently referred to as such.
Domestic angelfish have been bred and crossbred for several decades. There are hundreds of mutations of little importance by themselves. Much of the research into the known genetics of P. scalare is the result of the research of Dr. Joanne Norton, who published a series of 18 articles in Freshwater and Marine Aquarium (FAMA) Magazine. Those articles are reprinted at http://theangelfishsociety.org/genetics.htm .

Common Phenotypes
Silver (+/+)
The most commonly pictured form, this is also referred to as "wild-type", this type of fish does not contain any dominant color genes and at most a single dose of any recessive genes. Has silver body with 4 vertical black stripes. The stripes will fade and darken with mood. (Under stress will fade, darkest when breeding)
Gold (g/g)
One of the hardiest and most attractive strains. Some will develop an intense orange crown. Gold is a recessive trait, like blue eyes in humans
Zebra (Z/+ or Z/Z)
A Silver with extra stripes. A very popular strain.
Black Lace (D/+) / Zebra Lace (D/+ - Z/+)
A Silver or Zebra with one copy of the Dark gene. This results in very attractive lacing in the fins. Considered by some to the most attractive of all angelfish varieties.
Smokey (Sm/+)
A variety with a dark brownish grey back half and dark dorsal and anal fins.
Chocolate (Sm/Sm)
Homozygous foHalfblack (h/h)
Silver with a black rear portion. Halfblack can express along with some other color genes, but not all. The pattern may not develop or express if the fish are in stressful conditions.
Smokey with more of the dark pattern. Sometimes only the head is silver.

http://en.wikipedia.org/wiki/Freshwater_angelfish