AquariumHQ
Search
Worst case: Act within days4 possible causes

Snails are dying

Snails die, become inactive, or their shells pit and erode.

Short answer

Shell erosion means the water is too soft or too acidic. Sudden death usually means copper or a parameter change. And an inactive snail is not necessarily a dead one — check before removing it.

Check these first, in this order

  1. Test GH and KH. Shell maintenance needs calcium and carbonate.
  2. Has anything been added — medication, fertiliser, algaecide?
  3. Is the snail actually dead? A dead snail has a distinctive strong smell.
  4. Is a mystery snail able to reach an air gap at the surface?

Possible causes

Ordered by urgency, then by how commonly each one turns out to be the answer. The discriminator is the observation that separates this cause from the others — use it before acting.

Copper exposure

Act nowcommon

How to tell: Sudden deaths following a treatment or fertiliser, with fish unaffected.

Check

  • Read the ingredients of anything recently added

Response

  • Large water changes and activated carbon
  • Move survivors to a clean tank if possible

Trapped upside down or unable to reach air

Act todaycommon

How to tell: A mystery snail on its back on the substrate, or a tank filled to the rim so an air-breathing snail cannot reach the surface.

Check

  • Whether the snail is inverted
  • Whether there is an air gap above the water

Response

  • Turn it the right way up
  • Lower the water level to leave an air gap of a few centimetres

    Water too soft or too acidic

    Act within daysvery common

    How to tell: Shells pit, thin and erode at the apex over weeks to months. GH or KH is low.

    Check

    • GH
    • KH
    • pH
    • Shell condition

    Response

    • Raise GH and KH gradually with a remineralising product or crushed coral.
    • Existing shell damage does not repair, but new growth will be sound.

    Starvation

    Act within dayscommon

    How to tell: A nerite in a spotless tank, or several snails added at once to a tank with limited algae.

    Check

    • Whether there is visible algae or biofilm
    • How many snails per surface area

    Response

    • Feed algae wafers or blanched vegetables
    • Reduce the number of snails to what the tank can support

      What not to do

      • Copper-based treatments in any tank containing invertebrates
      • Removing an inactive snail before checking whether it is alive

      Prevention

      • Maintain adequate GH and KH
      • Check every product for copper
      • Feed snails deliberately in clean tanks