The Red-Bellied Pacu, Piaractus brachypomus, is a large freshwater fish native to the Amazon and Orinoco river basins in South America. This species, often mistaken for its relative the piranha due to similar body shape and size, is distinguishable by its more square, less razor-sharp teeth, adapted for crushing nuts and seeds rather than tearing flesh. This dietary difference reflects their omnivorous nature, contrasting with the carnivorous piranha.

Pacu fish, including the Red-Bellied Pacu, can reach significant sizes in the wild, often growing to impressive lengths. They exhibit a deep-bodied shape, and as their common name suggests, they have a distinctive red or orange hue on their belly, especially pronounced in juveniles and fading somewhat as they mature. The rest of their body is generally silver or grey, making the vibrant belly a striking feature.

Red-Bellied Pacus are known for their peaceful temperament, especially when compared to their piranha cousins. However, due to their large size and schooling nature, they require spacious aquariums or ponds that can accommodate their growth and activity. They are sociable fish that do well in groups, but their tank mates should be chosen carefully to ensure compatibility, particularly avoiding much smaller species that might be outcompeted for food or inadvertently injured.

In terms of care, providing an environment that closely mimics their natural habitat is crucial for the well-being of Red-Bellied Pacus. This includes warm, well-oxygenated water with plenty of space to swim. Decorations and plants are not just for aesthetics but also provide hiding spots and reduce stress, contributing to their overall health. A varied diet is essential, consisting of plant material, fruits, nuts, and commercial foods formulated for large omnivorous fish to ensure nutritional balance.

Red-Bellied Pacus have a fascinating reproductive strategy in the wild, involving migration to specific spawning areas during the rainy season, where they release eggs into the water to be externally fertilized. Reproducing these conditions in captivity is challenging, making breeding efforts less common among casual aquarists.

Despite their appealing appearance and interesting behaviors, potential keepers must consider the long-term commitment required to care for Red-Bellied Pacus. Their considerable adult size and dietary needs make them suitable primarily for experienced aquarists with the resources to provide adequately for their care. Additionally, their status as an invasive species in some non-native environments highlights the importance of responsible pet ownership and ensuring that they are not released into the wild, where they can disrupt local ecosystems.

Conservation efforts and regulations aim to balance the popularity of Red-Bellied Pacus in the aquarium trade with environmental protection, emphasizing sustainable practices and awareness to protect these unique fish and their natural habitats.