Bladder snail

Overview

Bladder snails (Physella acuta) are the small, fast-moving snails that appear in almost every tank eventually, arriving unseen as plant hitchhikers. Despite a pest reputation they’re genuinely useful — grazing algae, biofilm and leftovers while leaving healthy plants alone. The only real issue is speed of breeding, and that’s a feeding problem you control, not damage the snails do. They’re also a handy live indicator: a thriving bladder-snail population usually means your water is safe enough for more sensitive livestock, since these snails suffer before most fish or shrimp show any stress.

Tank & water

A 19 litre (5 gallon) tank is more than enough; bladder snails thrive in almost any stable setup and even tolerate less-than-perfect water:

• A cycled tank — cycle fully; they still do better without ammonia and nitrite spikes.
• Some hardness — pH above 7 with a little hardness keeps shells solid; very soft water erodes them.
• Calcium — minerals prevent thin, pitted shells.
• No copper — lethal to snails and shrimp; check medication and fertiliser labels.

Feeding

Bladder snails are detritivores that graze algae, biofilm and leftover food, so a normal tank feeds them with no effort at all. Deliberate feeding is never needed; every extra scrap of food simply speeds up their breeding, so the fix for too many snails is almost always less food. Rather than fighting them, many keepers simply accept a modest population as free clean-up crew and let the tank’s food supply set a natural ceiling on their numbers.

Tankmates & breeding

Bladder snails are entirely peaceful and coexist with any community fish, shrimp and snails. They reproduce rapidly and can self-fertilise, so populations grow fast in a well-fed tank. To control them, feed less and add an assassin snail, which hunts and eats them.

Compare with the coiled ramshorn snail and the burrowing Malaysian trumpet snail.