Copadichromis chrysonotus

Adults can reach a length of about 16 cm, with females typically being somewhat smaller. Their main coloration is blue or sky blue, with barely noticeable vertical dark stripes on the sides. Outwardly, Copadichromis chrysonotus resembles Copadichromis azureus, but differs from it by its light-colored back, which formed the basis of its name.

Being endemic to Lake Nyasa, a large African body of water located in the Rift Valley on the border of Malawi, Tanzania, and Mozambique, this species is widespread throughout its waters. The fish prefer to stay in large shoals in the upper water layers, where there is plenty of plankton.

These fish are distinguished by their peaceful and calm disposition if kept in very spacious aquariums, of several thousand liters. However, in confined conditions of limited space, males may compete with each other. It is recommended to keep them in a harem-type group, where there are several females per male. They get along well with other species that can adapt to an alkaline environment with high general water hardness.

Copadichromis azureus requires extensive open swimming areas. Therefore, for a group of 3–4 individuals, an aquarium of at least 350–400 liters with a height of 60 cm or more is recommended. Stone formations should be placed on the bottom, reaching the middle height of the tank, forming caves and grottoes within them. Any decorative elements can serve as shelters. Females can find refuge there during the incubation period, as well as fry. It is important to maintain water parameters characteristic of Lake Nyasa (extremely high pH and dGH values), as they differ significantly from other natural bodies of water and are critically important for the long-term well-being of this species. Aquarium maintenance traditionally includes weekly partial water changes, regular removal of organic waste, and prophylactic equipment care.

In their natural environment, zooplankton forms the basis of these fish's diet. In a home aquarium, they adapt well to most common dry foods, such as flakes and pellets. The diet can be enriched with live or frozen invertebrates, such as bloodworms, Artemia, or large Daphnia.

Mouthbrooding of fertilized eggs is a characteristic feature of all Lake Nyasa cichlids. This evolutionarily developed mechanism for protecting offspring arose under conditions of high competition. Most species usually spawn in nests specially arranged by males on the bottom. However, Copadichromis azureus is unique in that it is the only species in the lake that spawns in the water column. During the mating ritual, the female releases eggs and immediately picks them up before they can sink to the bottom. At this moment, the male manages to fertilize them. The incubation period lasts about a month. The hatched fry are already quite large and can feed on Artemia nauplii, as well as finely crushed dry flakes and pellets.

The main reason for most diseases often lies in unsuitable keeping conditions. At the first signs of illness, it is necessary to thoroughly check the water parameters, evaluate the fish's diet, and identify possible injuries that may have been sustained due to aggression from other aquarium inhabitants. Identifying and eliminating the root causes often leads to self-recovery, as the fish's body copes with the ailment. Nevertheless, in some cases, medication may be required; more information can be found in the "Diseases of Aquarium Fish" section.

When selecting individuals, attention should be paid to their activity and the absence of external damage, such as ulcers, film, or fin rot. A healthy fish should show interest in its surroundings, rather than staying sluggishly at the bottom or surface. Avoid purchasing fish with sunken bellies, which may indicate emaciation or internal parasitic infections. In store aquariums, individuals often appear paler than in their natural environment, but the bright coloration of males with a characteristic golden stripe on their back is a sign of good condition and absence of severe stress. It is recommended to acquire a group of several individuals, as this species adapts better and exhibits natural behavior as part of a harem.