Geophagus sveni, a member of the cichlid family, is a striking and relatively rare species of freshwater fish native to South America, particularly found in the waters of Brazil. As a part of the Geophagus genus, these fish are known as "earth eaters," a name that derives from their unique feeding behavior where they sift through substrate to extract food.

Geophagus sveni is distinguished by its colorful and dynamic appearance. It typically displays a body color of deep, iridescent blue or green with red highlights, especially around the face, belly, and fins. The body is laterally compressed with a prominent forehead, and the fins are often elongated and flowing, adding to their graceful demeanor in water.

In captivity, Geophagus sveni requires a specific set of conditions to thrive. They do best in large aquariums where there is ample space to swim and sift through the substrate. The tank should have a sandy or fine gravel bottom which allows them to engage in their natural digging behaviors without harming themselves. Decorations should include rocks and driftwood, which provide hiding spots and break lines of sight, reducing stress and aggression among tank mates.

Water conditions should mimic their natural tropical environment—soft to moderately hard, slightly acidic to neutral pH, and a temperature range that is typically warm. Regular water changes are crucial to maintain the high water quality necessary for their health, as they are sensitive to pollutants.

Geophagus sveni is generally peaceful but can show territorial behavior, particularly during breeding. They are best kept with other South American cichlids of similar size and temperament and can coexist with other fish that occupy different water column levels and are not small enough to be considered prey.

Their diet should be varied and include both plant and animal matter. High-quality cichlid pellets, flakes, and live or frozen foods such as worms, brine shrimp, and crickets should form the basis of their diet, supplemented with vegetable matter like spirulina, peas, and zucchini.

Breeding Geophagus sveni can be a rewarding experience. They are substrate spawners, typically laying their eggs on a flat rock or dugout pit in the sand. The parents exhibit biparental care, with both the male and female actively participating in the protection of the eggs and fry. The breeding tank should have subdued lighting and be set up to ensure the water conditions are stable to encourage spawning and successful rearing of the young.

Overall, Geophagus sveni is an excellent choice for advanced aquarists who appreciate the nuances of keeping South American cichlids. Their beautiful appearance, intriguing behaviors, and the care they require make them a rewarding addition to any suitable home aquarium.