Cherry shrimp (Neocaridina davidi)

Overview

Neocaridina davidi is a small freshwater shrimp of the family Atyidae and the most popular aquarium shrimp. The name "cherry shrimp" comes from the red selectively bred form; the wild type is a mottled, semi-translucent brown-green.

It is valued for being undemanding, breeding quickly and cleaning up leftover food, algae films and detritus. It suits beginners and nano tanks.

Breeders have produced many colour forms: red, orange, yellow, green, blue, violet, white, clear and more. All belong to one species and interbreed freely.

Appearance

Adults reach 2.5–4 cm (Tetra), about 3–4 cm (English Wikipedia); males are around 2 cm. The body is semi-translucent, elongated and laterally compressed, with a shell covering the cephalothorax.

The wild type is mottled brown-green; aquarium forms vary by strain. Colour intensity is very changeable: shrimp darken on dark substrate and may turn almost colourless under stress, e.g. after transfer.

Sex differences:
- females are larger, stouter and more intensely coloured;
- females show a "saddle" on the back — yellow or green ovaries with developing eggs;
- males are smaller, paler and more active.

Care

• Tank size: a small group (up to 10) can live in 5–10 L, but because sudden changes stress them Tetra recommends 30–50 L; Russian Wikipedia gives 20–30 L as suitable, with several dozen shrimp in 40–50 L. Rule of thumb: 1–2 L of water per shrimp.
• Group: keep in a group, ideally 10 or more.
• Temperature: optimum 22–25 °C (Tetra), 23–25 °C (Wikipedia); they tolerate 15–30 °C for a while.
• pH: 6.5–8.0 (Russian Wikipedia gives 7.5–8 for the cherry shrimp).
• Hardness: GH 6–20 (Tetra, colour forms), 2–10 °dH (Wikipedia, genus Neocaridina); KH 3–10 (another Tetra article gives 3–20). In very soft water the shell becomes too weak.
• Plants and moss: live plants are essential as cover, especially during moulting: Java and Christmas moss, Riccia, Cladophora, ferns; driftwood covered with moss is useful.
• Substrate: fine, 0.5–1.5 mm; shrimp look brighter on dark substrate.
• Filtration: a filter with gentle flow plus aeration, e.g. a small internal or air-driven (sponge) filter.
• Lid: cover the tank — shrimp climb out and jump when startled.
• Copper: copper compounds are highly toxic; copper-based fish medications and snail killers are dangerous.
• Water quality: sensitive to ammonia, nitrite and nitrate — add only to a mature tank.
• Water changes: up to 20% weekly.

Lifespan is 1–2 years (Tetra: a year to a year and a half); the warmer the water, the shorter the life.

Feeding

Omnivorous. Feeds on biofilm, algae, detritus and its own moulted exoskeletons; it does not eat vascular plants.

In a community tank leftover fish food is usually enough, but shrimp should also get specialised crustacean food (granules, sinking sticks, wafers). They accept blanched spinach, zucchini, oatmeal, pieces of vegetables and fruit, lettuce, and oak or hazel leaves — remove uneaten remains.

Tetra advises feeding once a day as much as is eaten within 2–3 hours in a shrimp-only tank; Russian Wikipedia suggests 1–2 feedings a week in a species tank. Tetra does not recommend high-protein live or frozen food.

Moults need not be removed — the shrimp eat them.

Compatibility

Completely peaceful but vulnerable because of its small size: small invertebrates are natural food for most fish. Juveniles and freshly moulted shrimp are most at risk.

• Good tankmates: guppies, mollies, neon tetras, danios, celestial pearl danios, otocinclus, bristlenose plecos, small tetras, corydoras, small rainbowfish; snails and other shrimp (Amano, filter shrimp).
• With caution: swordtails, gouramis.
• Unsuitable: any cichlids (even dwarf), large and predatory fish, angelfish, loaches, barbs, large rainbowfish, crayfish; predatory Helena snails catch juveniles.
• Planarians are also a danger.

Colour forms of Neocaridina interbreed easily, so different forms are kept apart to preserve colour.

Breeding

Breeding is easy and needs no special conditions — just a pair, stable water and food. There is no larval stage.

• Sexual maturity: about 2 months (English Wikipedia), about 3 months (Tetra).
• After moulting the female releases pheromones and males swim about searching for her. The male deposits sperm, and the eggs are fertilised as they leave the female's body.
• The female carries 20–30 eggs on her pleopods, fanning and cleaning them. Young or stressed females may drop their eggs.
• Eggs develop in 2–3 weeks; dark eye spots appear shortly before hatching.
• Fully formed shrimp of about 1 mm hatch as miniature adults. They need no special food, grazing on biofilm and microorganisms. Dense plants and moss give them cover.

To keep colours bright, breeders select the most intensely coloured shrimp and add new bloodlines from time to time.

Fun facts

• The species was described by E.-L. Bouvier in 1904 in the genus Caridina; the genus Neocaridina was only separated in 1938.
• The world population is thought to number in the billions, mostly in aquariums.
• Colour is produced by pigment cells called chromatophores (erythrophores, xanthophores, iridophores, leucophores, melanophores); carotenoids for pigment come from food.
• A shrimp can pale or brighten quickly as its pigment cells contract or expand.
• The female fans her eggs with her swimming legs to keep them supplied with oxygen.
• In Europe and the USA the species is considered invasive in warm discharge waters.