The Chocolate Doradid, scientifically known as Oxydoras niger, is a unique and eye-catching catfish species originating from the Amazon River basin in South America. Here's some information about the Chocolate Doradid:

- Size: The Chocolate Doradid can grow up to 12-15 inches (30-38 cm) in length, making it a relatively large catfish species.

- Appearance: As the name suggests, the Chocolate Doradid has a beautiful chocolate-brown coloration throughout its body. It has a sleek and elongated shape with a high dorsal fin and prominent pectoral fins.

- Habitat: This species is found in rivers and tributaries with slow to moderate water flow, often in areas with sandy or muddy substrates. They prefer areas with plenty of hiding spots, such as submerged logs, vegetation, and rocky formations.

- Behavior: Chocolate Doradids are generally peaceful and non-aggressive, but they can become territorial when kept with similar species. They are primarily bottom-dwellers and spend most of their time scavenging for food.

- Diet: In the wild, Chocolate Doradids are omnivorous, feeding on a variety of foods including insects, crustaceans, small fish, and plant matter. In captivity, they can be fed a well-rounded diet consisting of high-quality pellets, frozen or live foods such as bloodworms, brine shrimp, and chopped meaty foods like shrimp or fish.

- Aquarium Requirements: Due to their size, Chocolate Doradids require a spacious aquarium with a minimum capacity of 75 gallons (284 liters) for a pair. Provide them with plenty of hiding spots created by caves, driftwood, and rocks. The water should be well-filtered with a temperature range of 75-82°F (24-28°C) and a pH level around 6.5 to 7.5.

- Compatibility: Chocolate Doradids can be kept with other large, peaceful fish species that are not aggressive or overly territorial. Avoid keeping them with small fish that can be seen as potential prey.

It's important to note that the Chocolate Doradid is a large and active fish that requires a suitable aquarium setup and careful consideration of its needs. Additionally, they may produce a considerable amount of waste, so efficient filtration and regular water changes are necessary to maintain good water quality.