Neocaridina davidi is a freshwatershrimp originating from eastern China and northern Taiwan and introduced in the rest of Taiwan, Japan, and Hawaii, which is commonly kept in aquaria. The natural coloration of the shrimp is green-brown, though a wide variety of color morphs exist, including red, yellow, orange, green, blue, violet and black shrimp. Full-grown shrimp reach about 4 centimetres (1.6 in) long. N. davidi shrimp are omnivores that may live 1–2 years. These shrimps have previously been classified as Neocaridina heteropoda and Neocaridina denticulata sinensis, however are now known as Neocaridina davidi which is based on the oldest known published description of the species.[5]
N. davidi is a non-aggressive shrimp. They are active throughout the day and can be seen grazing on biofilm, aquarium décor or the sides of the tank, hunting detritus among the gravel, and sometimes even mating. Periodically, a shrimp will shed its exoskeleton, leaving an empty white ghost of itself caught in the plants or drifting around the tank. Juvenile shrimp will molt more frequently, as they must shed their exoskeleton as they grow. This discarded exoskeleton should be left in the tank, as the shrimp will eat it to recover the valuable minerals it contains.
Pregnant N. davidi shrimp tend to hide in the dark. If they feel endangered by predators, they will abandon their eggs. They need an environment with wood or plants such as Java moss in which to hide themselves and their babies. When they are carrying the eggs under their bodies, they can be witnessed circulating water over the eggs with their pleopods (swimming legs) to ensure good health.
N. davidi shrimp are primarily biofilm eaters.[6]N. davidi are omnivorous, which means they eat both plant and animal-based foods. They require a balanced diet to maintain optimal health and growth.
Neocaridina davidi have noticeable sexual dimorphism. The male is smaller and usually less colorful than the female. The male's tail, not being needed to carry eggs, is narrower. The female is larger and usually displays a richer, more opaque coloration, however selective breeding can produce males with similar quality of coloration. On the upper section of the female's body, on the "shoulder", the developing eggs on the ovaries may be seen in more transparent individuals. The color of these eggs will depend on the breed of individual shrimp. The shape of the ovaries drapes across both sides of the shrimp, giving rise to the nickname "saddle". The presence of a "saddle" indicates a female that is likely ready to mate.[7]
N. davidi shrimp reach sexual maturity when they are around 2–3 months old. Breeding only requires a sexed pair of shrimp, stable water parameters, and a food source. Eggs may be observed developing in the female's ovaries as a green or yellow triangular "saddle" marking on her back. When she is ready to lay the eggs, which occurs after molting, she releases pheromones into the water to signal her availability to males. The male shrimp in the tank will often become agitated, swimming very actively about as they search for the source of the pheromones. After a brief mating process, during which the male deposits sperm onto the female's body, the female lays her eggs and affixes them to her swimmerettes.
The eggs are not fertilized within the female; they are fertilized as they pass from the ovaries to the outside of the body. Therefore, it is certain that any shrimp carrying eggs has mated.
A two day-old Neocaridina davidi (red morph) shrimp (roughly 1 mm (0.039 in) in length)
They have 20–30 eggs, which take 2–3 weeks to hatch. The eggs are green or yellow, depending on the color of the saddle. They turn darker and darker until the young shrimp hatch after about three weeks. As the eggs near the end stages of growth, tiny dark eye spots of the developing shrimp within can be observed. When the young hatch, they are tiny (roughly 1 mm (0.039 in)) copies of the adults. They have no planktonic larval stage. They spend their first few days of life hiding among plants or stones, where they are almost invisible, nibbling on the biofilm on the plants. They then emerge and graze on algae on tank surfaces and ornaments.[citation needed]
Neocaridina davidi kept in aquariums have a wide range of colors, mainly as a result of selective breeding, though wild N. davidi also exhibit color variation naturally. As most of these shrimp are half transparent, the color of N. davidi nearly always is a result of "blood" ("flesh", muscles etc.) coloration and "skin" (the chitin of the shell) coloration.
Red – Red is the most frequently sold morph. The presence of erythrophores causes the red color of the shrimp.
Yellow – The yellow color of the shrimp is caused by the presence of xanthophores.
Blue – Blue shrimp are caused by the presence of iridophores which reflect blue light, or absence of melanophores combined with blue/blueish flesh.
Green – Green shrimp is caused by the mixture of iridophores (that reflect blue light) and xanthophores.
Violet – Violet shrimp is caused by the mixture of iridophores (that reflect blue light) and erythrophores.
Chocolate – Melanophores that are a dark brown shade are present in this shrimp, though erythrophores or xanthophores can contribute to the brown or chocolate color of the shrimp.
Black – Black melanophores are present in this shrimp, or brown melanophores combined with blue/blueish flesh.
White – White shrimp are mainly caused by the absence of melanophores.
"Ghost" – "Ghost" shrimp do not have any pigment at all and appear transparent.
^Klotz, Werner; Karge, Andreas (2013). "Gattung Neocaridina Kubo, 1938" [Genus Neocaridina Kubo, 1938]. Süßwassergarnelen aus aller Welt [Freshwater shrimp from all over the world] (in German) (3rd ed.). pp. 131–6. ISBN978-3935175-90-6.
