Macrobrachium lanchesteri

The Ghost Shrimp, scientifically identified as Macrobrachium lanchesteri, is often confused with other translucent shrimp species like those from the Palaemonetes genus. Also known as the Ricefield or Whisker Shrimp, this species is a fantastic addition for hobbyists seeking a functional and active invertebrate. Originating from the slow-moving waters of Asia, they thrive in aquariums that replicate this environment, preferring gentle water flow and a mature setup with plenty of biofilm and detritus to graze on. Hiding places are essential; providing driftwood, leaf litter, and dense plantings like Java moss will give them security, especially during their vulnerable molting periods, and help mitigate their inherent territorial nature.

While labeled as 'easy,' understanding their social dynamics is key. As a member of the Macrobrachium genus (long-armed shrimp), they possess small claws and will establish a pecking order within a group. This can lead to minor sparring matches, which is why keeping them in a sufficiently large group in a tank of at least 20 liters is recommended to diffuse aggression. They are not predatory towards healthy fish, but their opportunistic omnivorous nature means they may attempt to scavenger on very small, sick, or dying tank mates.

Their role as a 'clean-up crew' is prominent. They tirelessly sift through the substrate, consuming a wide variety of organic matter. However, a diet based solely on scavenging is insufficient. Their health and exoskeleton development depend on a balanced diet supplemented with high-quality sinking pellets, wafers, and blanched vegetables. Calcium is particularly important for successful molting.

Reproduction in M. lanchesteri is a fascinating challenge that sets them apart from many common dwarf shrimp. They have a complex breeding cycle where the female carries eggs that hatch into free-swimming larvae. These larvae require a period in brackish water to develop and metamorphose into juvenile shrimp before they can return to freshwater. This specific requirement prevents them from reproducing in a standard freshwater community tank, but offers a rewarding project for the dedicated aquarist. A noteworthy behavioral trait is their propensity to escape the tank; any gaps in the lid, around filters or heaters, must be secured to prevent them from climbing out.

Macrobrachium lanchesteri, a decapod crustacean within the family Palaemonidae, is a benthic species native to freshwater and low-salinity habitats across Asia. Its physiological hardiness is evidenced by its tolerance for a broad pH spectrum and its osmoregulatory capacity to handle shifts in water hardness and total dissolved solids, making it a robust subject for study and aquaculture. Its metabolism is characterized as low, resulting in minimal oxygen consumption and waste production, which translates to a low bioload within a closed aquatic system. This efficiency makes it an effective detritivore and consumer of biofilm, playing a significant role in nutrient cycling by breaking down organic waste.

Behaviorally, M. lanchesteri exhibits intraspecific territoriality, a common trait in the Macrobrachium genus, often involving agonistic displays related to resource competition. While classified as having a moderate activity level, its behavior is primarily focused on foraging across the substrate. Its strong exploratory instinct, coupled with its physical ability to climb, results in a high potential for escaping unsecured aquaria.

Reproductive biology is a key distinguishing feature. M. lanchesteri exhibits an amphidromous life cycle with prolonged larval development. Following internal fertilization, the female incubates eggs on her pleopods. Upon hatching, planktonic zoea larvae are released. These larvae are physiologically dependent on brackish water for metamorphosis through several developmental stages into post-larvae. The post-larval stage marks the transition back to a fully freshwater benthic existence. This complex reproductive strategy prevents self-sustaining populations in standard freshwater aquaria and distinguishes it from fully freshwater-breeding shrimp like Neocaridina davidi or certain Palaemonetes species with which it is sometimes confused in the trade. Its widespread distribution and stable population in its native range have led to its IUCN classification as Least Concern (LC).