Atya gabonensis

The Gabon Fan Shrimp, also known as the Vampire or African Filter Shrimp, is a large and peaceful crustacean perfect for a community tank with the right setup. They are not predators; instead of claws, they have unique 'fans' that they use to catch tiny food particles floating in the water. This is why it's crucial to have a tank with strong water movement, as they love to find a spot in the current, open their fans, and wait for their meal to come to them. Because of their specialized feeding and need for high flow, they are considered slightly more challenging than other shrimp varieties.

These gentle giants are slow-moving and spend most of their time perched on driftwood or rocks. They are completely peaceful towards fish and other invertebrates. However, if you see them scraping the ground with their fans, it's a sign they are very hungry and not enough food is floating in the water. For feeding, you can crush fish flakes or algae wafers into a powder and release it into the current upstream from the shrimp. A key thing to remember is that these shrimp are known escape artists, especially when newly introduced to a tank, so a tight-fitting lid is essential.

Atya gabonensis is a fascinating invertebrate whose husbandry revolves around mimicking its natural habitat of fast-flowing West African rivers. A mature aquarium is highly recommended to ensure a stable supply of microorganisms and biofilm. The most critical element for their well-being is high water flow. This can be achieved using strategically placed powerheads or the output from a canister filter, creating currents where the shrimp can position itself for feeding. Ideal aquascaping includes smooth rocks and sturdy driftwood, which provide secure perches in high-flow zones and essential hiding places.

Their medium difficulty rating stems not from water parameter sensitivity, but from their specific feeding requirements. As suspension feeders, they rely on a constant supply of fine particulate matter. In a typical 'clean' aquarium, they can easily starve. A healthy, well-fed Fan Shrimp will remain stationary in a current with its fans open. If it begins walking the substrate and scraping surfaces with its fans, it is a clear sign of insufficient food in the water column. A dedicated feeding regimen is necessary, involving finely ground spirulina powder, crushed flakes, and specialized invertebrate foods mixed with water and released upstream of the shrimp using a pipette. This ensures the food is delivered directly into the current they inhabit.

These shrimp undergo a molting process to grow, shedding their entire exoskeleton. During this time, they are extremely vulnerable and will hide for several days. It is vital to provide ample hiding spots and to not remove the shed molt, as the shrimp will often consume it to reabsorb crucial minerals. Their breeding is exceptionally difficult in captivity. While females will carry eggs, the larvae require brackish or full saltwater conditions to develop before migrating back to freshwater. This complex reproductive cycle, known as amphidromy, makes successful home breeding nearly impossible.

In terms of social behavior, they are non-aggressive and can be kept singly or in groups. If kept in a group, ensure there are multiple prime feeding spots available in the current to prevent competition. They are excellent tank mates for peaceful, small-to-medium-sized community fish that will not harass them.

Atya gabonensis is a decapod crustacean belonging to the family Atyidae, a group renowned for its filter-feeding members. Its most notable morphological adaptation is the modification of its first two pairs of chelipeds into elaborate filter-feeding appendages. These 'fans' are composed of dense chelae armed with fine, plumose setae that effectively strain fine particulate organic matter (FPOM), phytoplankton, and zooplankton from the water column. When feeding, the shrimp orients itself rheotactically (facing into the current) and periodically sweeps the particle-laden fans across its maxillipeds and other mouthparts for ingestion. The third pair of pereiopods are notably robust and heavily built, an adaptation for securely gripping substrate in lotic environments with high-velocity flow. Sexual dimorphism is present; males possess a significantly larger and more robust third pair of pereiopods compared to females, while gravid females exhibit a broader pleon to accommodate egg clutches.

This species exhibits an amphidromous life cycle, a critical factor for its reproductive biology. After fertilization in freshwater habitats, the female incubates the eggs. Upon hatching, the planktonic zoea larvae drift downstream into brackish estuaries or marine environments. They undergo a series of larval stages (a process known as metamorphisis) in saltwater before developing into post-larval juveniles. These juveniles then undertake an upstream migration back into freshwater systems where they mature into adults. This complex life history makes captive propagation exceedingly challenging, a significant barrier to its widespread commercial aquaculture.

Ecologically, A. gabonensis functions as a primary consumer and a key component in nutrient cycling within its native West African river systems. By converting suspended organic detritus into biomass, it makes energy available to higher trophic levels. Its IUCN status is listed as Least Concern (LC), indicating a widespread and stable global population. However, its reliance on longitudinal river connectivity makes local populations vulnerable to anthropogenic impacts such as dam construction, which creates barriers to larval drift and juvenile migration, potentially isolating populations and leading to localized declines.