There are around 100 different species of angelfish that inhabit the waters of the southern hemisphere. There are two main types of angelfish, those that live in the freshwater rivers in South America (freshwater angelfish) and those angelfish that inhabit the salty ocean waters (marine angelfish).
The freshwater angelfish has a more triangular shape and will generally only grow to a few inches in length. The marine angelfish can grow up to 12 inches (the same length as a big ruler) and generally have very brightly coloured markings but the exact colours depend on the angelfish species.
Both the freshwater angelfish and the marine angelfish are known to be relatively difficult fish to keep in household aquariums, as both types of angelfish require very specific water conditions. Angelfish are very susceptible to changes in the water such as salt levels and pH levels, and will often die if changes are too drastic.
Despite the fact that their names are the same, freshwater angelfish and marine angelfish are not thought to be closely related. The freshwater angelfish is a tropical species of cichlid, distantly related to the cichlids found in specific lakes in Africa. The marine angelfish are believed to be most closely related to the butterfly fish.
Freshwater angelfish are native to the Amazon basin and are also found in the rivers running off it. Freshwater angelfish inhabit the cleaner waters and prefer to be in temperatures between 25 and 30 degrees centigrade.
Freshwater angelfish lay between 100 and 1,000 eggs which hatch in just a couple of days. Freshwater angelfish tend to lay their eggs on a flat leaf or an underwater log. The baby angelfish (known as fry) remain attached to the eggs for another week and feed off the remaining yolk in the egg sack. When they are bigger at a week old, the angelfish fry detach from their eggs and become free swimming. It is at this stage that the baby angelfish begin feeding from nutrients in the water and on plants.
The triangular shape of the freshwater angelfish, means that the angelfish is able to hide more easily amongst the aquatic plants in the water. Wild freshwater angelfish have very distinctive dark stripes that run vertically down their bodies, giving the freshwater angelfish the ability to blend in to it\'s surroundings. Freshwater angelfish usually breed for life and it is often found that if one of the angelfish parents dies, then the remaining angelfish parent has no interest in breeding.
Freshwater angelfish feed on smaller fish and invertebrates in their natural environment as well as eating particles of food found in the water. The freshwater angelfish is preyed upon by larger species of fish, birds and marine mammals.
Marine angelfish are generally found in shallow reefs in depths of up to 50 meters. Marine angelfish are reported to be almost fearless and are noted to be inquisitive and curious towards divers. Some species of marine angelfish are solitary by nature where other species of angelfish form territorial mating pairs or even groups. The groups of marine angelfish usually have one male and a number of females.
Unlike the freshwater angelfish, marine angelfish lay their tiny eggs straight into the water. The angelfish eggs float in the sea, becoming mixed in with the plankton, until they hatch. Unfortunately a vast number of marine angelfish eggs are inadvertently eaten by those many animals that feed on the plankton in the water.
Marine angelfish are most well known for the bright colours and patterns on their bodies. Marine angelfish vary in colour and size depending on the species of marine angelfish, although it is known that the patterns and colours of marine angelfish change drastically as they get older. It is believed that these colour changes indicate the position of the marine angelfish, within the marine angelfish social hierarchy.
Marine angelfish graze on algae on coral reefs and rocks are well as eating smaller fish and crustaceans such as shrimp and small species of prawn. Adult marine angelfish are preyed upon by sharks, marine mammals and humans, but the young and smaller marine angelfish are eaten by many different species of animal both in the water and those based on land (such as birds).