Shrimp-safe parameters, and the numbers that quietly kill

Dwarf shrimp do not act sick. A fish in trouble hangs at the surface, clamps its fins, breathes hard at the glass. A shrimp gives you almost none of that. It moults, or it fails to moult, and one morning there's a body on the substrate that wasn't there the night before. By then the cause is already a day or two in the past.

So you keep shrimp by watching the numbers, not the animals. This guide is the parameter window where colonies actually thrive, and then the short list of things that kill shrimp while everything else still reads fine.

Two genera, two completely different tanks

The most common shrimp mistake is treating "shrimp" as one care sheet. There are two genera in the hobby, and they want opposite water.

Neocaridina are the cherry shrimp and their colour morphs: red cherries, blue dreams, yellow neon, orange sakura. Hard-water animals, genuinely forgiving, the right starting shrimp for almost everyone.

Caridina are the crystal reds and blacks, the bee shrimp, the Taiwan bees (king kong, panda, blue bolt, wine red). Soft-water animals, bred over generations to a tighter window, and unforgiving of mistakes that a cherry would shrug off.

Put a caridina in cherry water and it lingers a few weeks, stops breeding, and slowly disappears. The reverse is gentler but still wrong. People talk about these as easy-mode and hard-mode versions of the same animal, but that framing has sunk a lot of colonies. They want different substrate, different minerals, and a different pH band. Build for one or the other.

Parameter	neocaridina	caridina
GH	6–12	4–6
KH	2–8	0–2
pH	6.5–7.5	5.5–6.5
TDS	150–300	100–150
Temp	18–24 °C	20–24 °C

The KH row is where the two worlds split most sharply, and it's worth understanding why rather than just copying the numbers.

Why caridina want zero KH

Caridina are kept on an active buffering substrate: ADA Amazonia, Fluval Stratum, Brightwell Shrimpset and the like. These soils pull KH toward zero and hold pH down in the 5.5 to 6.5 band. That low pH is part of the care requirement, not an accident, and it only stays stable if there's no carbonate hardness fighting it.

This is the bit that trips people up. Add KH to a caridina tank and you're working against the soil: the pH drifts up and the soil burns through its buffering capacity faster trying to drag it back. So for caridina you target GH only and leave KH at or near zero. The soil does the pH work.

Neocaridina don't use buffering soil. They sit happily in the lightly buffered range that ordinary remineralised water or moderately hard tap gives you, where a KH of 2 to 8 stops the pH from swinging. The GH-versus-KH guide covers the two hardness types if the distinction is still fuzzy: GH is what shrimp use to build shells, KH is the pH shock absorber.

Remineralising RO, the practical bit

Most serious shrimp keepers run RO or distilled water and add minerals back; it's the only way to hit an exact GH and TDS regardless of what comes out of the tap. The salts are genus-specific:

• Neocaridina: a GH/KH+ remineraliser (the Salty Shrimp GH/KH+ blend is the reference). It raises both GH and KH together, which is what hard-water shrimp want.
• Caridina: a GH+ only product. Salty Shrimp Bee Shrimp Mineral GH+ raises GH without touching KH, so the buffering soil keeps the pH where it belongs.

Mix the salt into the RO water to your target before it goes near the tank; dosing minerals straight in gives you a TDS spike exactly where the animals live. The hardness converter helps translate between °dGH, ppm, and the figures on the salt bag, which don't always match your test kit's units.

A caveat the forums tend to skip: tap water is fine for neocaridina more often than people admit, if it's stable and roughly sits in the GH 6 to 12, KH 2 to 8 range. RO plus remineraliser is the reliable path, not the only one. For caridina it really is the only sensible path.

The quiet killers

The parameters above describe the window. What follows breaches it without warning, and a tank can read perfectly on a test strip while one of these is already killing the colony.

Copper

Copper is the big one. Trace amounts of dissolved copper are lethal to invertebrates at concentrations fish don't even notice, and it arrives from places that look harmless:

• Fish medications. Anything for ich, velvet, or external parasites is very often copper-based. A dose calibrated for fish is a death sentence for a shrimp tank.
• Some plant fertilisers. Copper is a micronutrient, so it shows up in trace mixes. A normal plant dose is usually fine, an overdose is not, and "shrimp-safe" on the label is worth confirming rather than trusting.
• Copper plumbing. Pipework can leach into soft, low-pH water, which is more aggressive at dissolving metals. Caridina tanks are the most exposed because their water is the softest.

Read every label before it touches a shrimp tank. If a medication is copper-based, the shrimp come out into a separate container first and don't go back until the tank has been water-changed clean. There is no safe trace level you can dose past. The copper reference page has the toxicity figures, but the practical rule is simpler: keep it out.

Unstable GH and the failed moult

Shrimp grow by shedding their shell and building a larger one, pulling the calcium and magnesium for the new shell straight out of the water column. That's what GH supplies. When GH is too low, or worse, when it lurches around between water changes, the new shell doesn't harden correctly and the animal gets stuck mid-moult.

The visible sign is the white ring of death: a pale gap at the back of the neck where the old and new shells should have separated cleanly. A shrimp showing it is usually beyond saving. The cause is almost always GH that's too low or too variable.

What fixes it is stability, not just a number on the day you tested. Hit a GH inside the range and then hold it there. This is the argument for remineralising to a fixed target instead of topping up with tap: you get the same GH every single time, with no slow drift to fail a moult against. The GH page has the moult chemistry in more detail.

Nitrate, temperature, and the cycle

These three kill slowly enough to slip past you.

Nitrate. Shrimp tolerate less NO₃ than fish do, and breeding colonies are fussier than the adults you already keep. Aim to keep it under about 20 mg/L. High nitrate suppresses breeding long before it kills anything, so a colony that "just stopped having babies" is often a nitrate story. The feeding-nitrate calculator is worth a look if yours keeps creeping up, since overfeeding is usually the source.

Temperature swings. A steady 22 °C beats a tank that rides 19 at night and 25 by afternoon. Metabolism, moult timing, and oxygen demand all track temperature, and a fast swing stresses all three at once. Stable matters more than the exact figure.

Ammonia and nitrite during cycling. This one is absolute: never cycle a tank with shrimp in it. The spikes of an establishing tank are lethal to invertebrates, and shrimp won't show you they're in trouble until they're dead. A shrimp tank runs its full nitrogen cycle empty, reads clean zeros for NH₄ and NO₂ for at least a week, and only then gets shrimp.

TDS as the holistic check

Total dissolved solids is a rough sum of everything ionic in the water: the GH and KH minerals, the salts, the trace nutrients, accumulated waste. On its own a TDS number tells you little. As a trend, it tells you a lot.

A stable shrimp tank holds a stable TDS. So if your caridina tank has sat at 130 for months and suddenly reads 165, something changed: minerals leaching, evaporation concentrating the water, a fertiliser you forgot you dosed. The number alone won't say what, but it tells you to go looking. A sudden TDS jump is the smoke alarm, the first reading I check on a tank that "seems off" but tests fine on everything else.

Acclimation: go slow

Bringing new shrimp home is where a lot of healthy stock dies in the first hour. Shrimp don't handle sudden shifts in TDS, pH, or temperature, and the gap between the shop's water and yours can be large.

Drip acclimate. Float the bag to match temperature, then run a slow siphon (an airline with a knot or a control valve) into a container holding the shrimp, two or three drops a second. Over an hour or two the volume should roughly triple, so the shrimp end up in water that's mostly yours. Then net them across; don't pour shop water into your tank. A 20-minute float-and-dump is fine for hardy fish and a real risk for shrimp.

Where this leaves you

Shrimp keeping rewards patience and punishes improvisation. Pick a genus and build the tank around it. Remineralise to a fixed target so GH and TDS don't wander between water changes. Read every label for copper, every time. And cycle the tank fully before a single shrimp goes in, then drip them across slowly when they do.

Then watch the numbers, on a schedule, the way you'd watch them for an animal that won't tell you when it's in trouble. Because that's exactly what you've got.