Found tiny bubble-shaped snails you never bought cruising your glass? Meet the bladder snail (Physa acuta) — the hobby's most famous hitchhiker. Before you declare war: they're not the villain they're made out to be. Here's the honest guide to what they do, when to worry, and what to keep instead if you want snails that earn their place.
How did they get in?
Eggs hitchhike on plants, driftwood, even in a bag of gravel. A single clutch is enough — bladder snails are hermaphrodites and can self-fertilise, so one snail becomes a colony within weeks.
Identification: bladder snail vs pond snail
- Shell spirals LEFT (sinistral) — the giveaway; pond snails spiral right
- Small (≤1.5 cm), thin translucent shell, speckled body, long thin antennae
- Zig-zag "skating" swim along the surface film
Are they actually bad? (Honest answer: no)
Bladder snails eat algae, uneaten food, decaying plant matter and carrion — they do NOT eat healthy plants (their mouthparts can't manage living leaves). A stable population is a free clean-up crew. The real problem is what a boom tells you: snail numbers track food supply, so an explosion means you're overfeeding. Fix the feeding, and the population shrinks on its own — same principle as in our feeding guide.
Controlling an outbreak
- Cut feeding — the only fix that lasts; everything else treats symptoms
- Manual removal — lettuce leaf overnight, lift it out covered in snails each morning
- Rinse new plants — quick inspection + rinse before anything enters the tank
- Never use chemicals — copper-based snail killers also kill shrimp and beneficial bacteria (see why shrimp die)
Skip assassin snails as "the fix" — they work, then you have an assassin snail population instead. Address the food supply.
Want snails that earn their keep? Keep these on purpose
- Nerite snails — the best algae eaters in the hobby, and they can't breed in freshwater — zero population risk
- Mystery snails — big, colourful (gold, purple, chestnut), peaceful — the "pet" snail
- Red ramshorn snails — stunning colour and tireless cleaners; more in ramshorn pros & cons
- Malaysian trumpet snails — burrow and aerate your substrate while cleaning it
Full comparison: best tank mates for mystery & nerite snails.
FAQ
Will bladder snails harm my shrimp or fish?
No — completely peaceful. They coexist happily with shrimp and community fish.
Can I just leave them?
Absolutely. Many keepers do — free cleaning, fish snacks (many fish eat them), and a live indicator of your feeding levels.
🛒 Shop this guide
Sydney-conditioned · shipped Australia-wide · Live Arrival Guarantee
Upgrade your clean-up crew
Browse our aquatic snail collection — nerites, mysteries, ramshorns and native species, all bred or conditioned in Sydney and shipped with a Live Arrival Guarantee.
