Onion Snail (Melanoides granifera)

Overview

The Onion Snail is a small freshwater snail known for its rounded, onion-shaped shell and burrowing behavior. It is often confused with the Malaysian Trumpet Snail (Melanoides tuberculata), but it is a distinct species with a shorter, more bulbous shell.

• Scientific name: Melanoides granifera

• Common name: Onion Snail

• Family: Thiaridae

• Origin: Southeast Asia

• Lifespan: 1–2 years

Physical Characteristics

• Size: 0.5–1 inch (1–2.5 cm)

• Shell shape: Short, rounded, conical (onion-like)

• Shell color: Brown, tan, or olive, often speckled

• Body color: Gray to dark brown

• Operculum: Present (hard “trapdoor”)

Compared to Malaysian Trumpet Snails, onion snails are:

• Shorter and thicker

• Less elongated

• More visible during daylight

Natural Habitat

• Slow-moving rivers, ponds, and lakes

• Sandy or muddy substrates

• Warm tropical climates

They naturally burrow to avoid predators and temperature changes.

Behavior

• Peaceful and non-aggressive

• Spends much of its time burrowed in substrate

• Emerges mainly to feed

• Active both day and night

Their burrowing helps aerate substrate, which benefits planted aquariums.

Diet

Onion snails are detritivores and algae grazers.

They eat:

• Algae and biofilm

• Decaying plant matter

• Leftover fish food

• Sinking wafers or pellets

• Blanched vegetables (zucchini, spinach)

They do not eat healthy plants.

Aquarium Care

Tank Size

• Can live in tanks as small as 5 gallons

• Larger tanks help prevent overpopulation

Water Parameters

• Temperature: 72–82°F (22–28°C)

• pH: 6.5–8.0

• Hardness: Soft to hard (adaptable)

• Ammonia/Nitrite: 0 ppm

• Nitrate: <20–30 ppm

They are hardy and tolerate a wide range of conditions.

Substrate

• Sand or fine gravel preferred

• Burrowing behavior makes sand ideal

• Avoid sharp gravel

Compatibility

Good tank mates:

• Peaceful community fish

• Shrimp

• Other non-aggressive snails

Avoid:

• Snail-eating fish (loaches, puffers)

• Crayfish

Reproduction

Onion snails reproduce very efficiently.

• Livebearers (give birth to live young)

• Can reproduce parthenogenetically (without mating)

• Populations can explode if excess food is available

This makes them useful as a “clean-up” species but also a potential pest.

Advantages and Disadvantages

Advantages

• Excellent substrate cleaners

• Hardy and adaptable

• Useful indicator of overfeeding

• Do not damage plants

Disadvantages

• Can overpopulate quickly

• Not decorative compared to larger snails

• Hard to remove once established

Common Issues

• Population boom: Usually caused by overfeeding

• Shell thinning: Low calcium or acidic water

• Mass emergence: Often indicates low oxygen or poor water quality

How to Control Population

• Reduce feeding

• Vacuum substrate

• Introduce natural predators (with caution)

• Manual removal

Summary

Onion snails are hardy, burrowing freshwater snails ideal for substrate cleaning and algae control, but they require population management. They are best suited for aquarists who understand the balance between feeding and bioload.