The ideal GH depends on the shrimp: Neocaridina, the common cherry shrimp and their colour forms, want a GH of roughly 6 to 12 dGH, while Caridina, the crystal reds and bee shrimp, want it far softer at around 4 to 6 dGH. GH matters more to shrimp than almost any other reading, because shrimp build a fresh calcium-rich exoskeleton every time they moult, and the water is where that calcium comes from.

Why GH is the reading that matters for shrimp

General hardness measures the dissolved calcium and magnesium in your water. Every time a shrimp moults it grows a new shell, and it draws the minerals for that shell straight from the water column. Too little GH and moults fail, producing the notorious white ring of death where the shell splits behind the head and the shrimp cannot free itself. Too much is rarely a problem for hard-water species, though it can shorten the softer Caridina.

The numbers by species

  • Neocaridina (cherry, blue, yellow, orange): 6 to 12 dGH is the sweet spot, and they tolerate more. My own tap runs 22 to 23 dGH and my cherry shrimp moult cleanly and breed constantly in it, so hard water is a genuine advantage here rather than a handicap.
  • Caridina (crystal red, bee): 4 to 6 dGH, paired with soft, slightly acidic water. These are a soft-water project and a poor fit for hard tap.

A quick FAQ

Is my water too hard for cherry shrimp? Almost certainly not. Neocaridina thrive in hard water, and the far more common failure is water that is too soft for a clean moult.

How do I raise GH for shrimp? If your source water is very soft, a remineralising salt made for shrimp lifts GH to target. RO users add it to every batch. Hard-water keepers rarely need to touch it.

GH or KH, which matters more for shrimp? GH, because that is the calcium and magnesium they build shells from. KH still matters for holding pH steady, but GH is the one shrimp physiology feels directly.

For the full picture on GH, KH and why hard, mineral-rich water suits so many aquarium animals, see the guide to keeping fish in hard water. For everything else about building a colony, read the cherry shrimp care guide.