Fishmoth is the common South African name for silverfish — the same silvery, teardrop-shaped insect that feeds on paper, starch, and fabrics. Use this guide to identify it and where it is found.

No. Silverfish do not bite or transmit disease. They can damage paper, books, wallpaper, and natural fabrics. They are mainly a nuisance and an indicator of humidity.

Why do I have silverfish in my bathroom?

Silverfish need humidity. Bathrooms provide moisture from showers and sinks. Reduce humidity with ventilation or a dehumidifier; seal gaps and fix leaks; professional treatment can target hiding places.

When should I get professional silverfish control?

When silverfish appear in multiple rooms, when there is damage to books or fabrics, or when DIY measures (reducing humidity, cleaning) have not stopped activity. We treat hiding places and advise on moisture control.

How do I use the quick comparison table?

Match what you see (colour, size, where found — bathroom vs near boiler) to the table to identify common silverfish (fishmoth), firebrat, or grey silverfish. Then read that species card for behaviour and when to get help.

Silverfish Identification Guide

Q: Silverfish vs firebrat — how do I tell them apart?

Common silverfish is silvery-grey and prefers humid areas (bathrooms, basements). Firebrat is mottled brown/grey and prefers warm areas (near boilers, hot pipes, attics). Both have three tail bristles and similar shape.

Silverfish (fishmoths) are small, wingless insects that feed on starch, paper, and fabrics. They prefer dark, humid places and are often seen at night. Correct identification — common silverfish vs firebrat (warmer areas) — helps you target the right areas and reduce humidity and food sources. This guide covers what they look like, where they are found, damage signs, and when to get professional silverfish control. They do not bite or transmit disease but can damage books, wallpaper, and clothing.

Identify silverfish (fishmoth) and firebrat. Know where they hide, what damage to look for, and when to get help.

Need silverfish control?

Call Get a quote See Silverfish Control

Silverfish on a bookshelf observed by a person — identification guide context; species cards describe common silverfish and firebrat

How to use this guide

Check shape and colour — teardrop-shaped, silvery-grey = common silverfish; mottled brown/grey = firebrat.
Note size — adults about 12–19 mm; three long tail bristles at the rear.
Note where you found them — bathroom, basement, cupboard, or near heat (firebrat prefers warm spots).
Look for damage — yellowing or notching on paper, books, wallpaper; holes or stains on fabrics.
Rule out lookalikes — earwigs have pincers; booklice are smaller and different shape; silverfish have no wings.
Then match to the species card using the quick comparison table; reduce humidity and treat hiding places.

Quick comparison

Silverfish / type	Colour	Size	Commonly found	Key clue
Common silverfish (fishmoth)	Silvery-grey; metallic sheen	~12–19 mm	Bathrooms, basements, cupboards; dark, humid	Fast, wriggling run; three tail bristles; nocturnal
Firebrat	Mottled grey, brown, tan	~12–15 mm	Near boilers, hot pipes, attics; warm areas	Prefers heat; similar shape to silverfish; three tail bristles
Grey silverfish	Grey; less metallic	Similar to common silverfish	Damp rooms, kitchens, bathrooms	Same habits; damage to paper and starch

Species at a glance

Use the cards below to match what you see — appearance, where they are found, and behaviour.

Common Silverfish (Fishmoth)

Lepisma saccharinum

Appearance

Teardrop-shaped; flattened; silvery-grey with metallic sheen
About 12–19 mm long; three long tail bristles at rear
Two long antennae; no wings; covered in scales
Moves with a fast, wriggling run

Commonly found

Bathrooms and kitchens (humidity)Basements and under sinksCupboards, bookshelves, and storageBehind wallpaper and in cracksAttics and roof spaces if damp

Behaviour

Nocturnal; prefers humidity (around 75% or higher) and temperatures from cool to warm. Feeds on starch, paper, glue, and natural fabrics. Can live several years. Leaves small faecal pellets and may shed scales. Does not bite; mainly a nuisance and damage to belongings.

Why you may be seeing them

High humidity, leaks, or poor ventilation; clutter and stored paper provide food and hiding places. Often seen when switching on a light at night or when moving stored items. Damage to books, wallpaper, or clothing indicates an established population.

Often confused with

Firebrat (firebrat is mottled brown/grey and prefers warm areas) · Earwig (earwigs have pincers at rear; different shape) · Booklouse (smaller; different body shape)

When to get help

Silverfish in multiple rooms; visible damage to books, documents, or fabrics; or repeated sightings after DIY measures. Professional treatment targets hiding places; reducing humidity is essential for long-term control.

In South Africa often called fishmoth. Reducing humidity (dehumidifier, ventilation) greatly helps.

Common silverfish pest guide Need silverfish control? See Silverfish Control

Firebrat

Thermobia domestica

Appearance

Similar teardrop shape to silverfish; mottled grey, brown, and tan
About 12–15 mm; three tail bristles
Long antennae; no wings; scaly body
Prefers warmer spots (above ~30 °C)

Commonly found

Near boilers, furnaces, and hot water pipesAttics and roof spaces (warm)Bakeries and commercial kitchensBehind ovens or hot appliances

Behaviour

Same diet as silverfish (starch, paper, glue) but prefers warm, dry-to-moist areas. Often found in heated commercial premises or warm corners of homes. Control by reducing heat/harbourage where possible and treating cracks and voids.

Why you may be seeing them

Warm spots in the building; new items or storage near heat sources. Less common than silverfish in typical homes but can be numerous in bakeries or buildings with constant heat.

Often confused with

Common silverfish (silverfish is silvery-grey and prefers humid, not necessarily hot) · Grey silverfish (grey silverfish in damp areas; firebrat in warm)

When to get help

Firebrats in large numbers or in sensitive areas (e.g. archives, storage). Treatment targets harbourage; improving ventilation and reducing heat where practical helps.

Identification by location (warm areas) is as important as appearance.

Firebrat pest guide Need silverfish control? See Silverfish Control

Common signs by location

Where you find silverfish — bathroom, cupboard, or near heat — points to the type and the right control. Reduce humidity and treat hiding places.

Bathroom or kitchen
High humidity attracts silverfish. Check under sinks, behind cabinets, and in corners. Reduce moisture and fix leaks.
Common silverfishGrey silverfish
Cupboards and bookshelves
Damage to paper, book bindings, or cardboard; small faecal pellets or shed scales. Store paper in dry, sealed containers.
Common silverfish
Basement or storage
Dark, damp storage is ideal. Dehumidify and reduce clutter; inspect boxes and books for damage.
Common silverfish
Near boilers or hot pipes
Firebrats prefer warmth. Seal gaps and reduce harbourage; treat if numbers are high.
Firebrat
Behind wallpaper
They feed on paste and paper. Peeling or damaged wallpaper can hide silverfish; treat wall voids and reduce humidity.
Common silverfish

Why silverfish keep coming back

Humidity remains high — bathrooms, leaks, or poor ventilation keep conditions ideal.
Food sources available — paper, cardboard, starch-based glue, and fabrics in cupboards.
Hiding places not treated — cracks, voids, and clutter provide refuge.
New items brought in — second-hand books or stored goods can introduce or re-introduce them.
No long-term moisture control — treatment without reducing humidity often leads to return.
Adjacent areas still infested — silverfish can move between rooms or from neighbouring units.

Common silverfish signs and behaviour

These patterns help you confirm identification and know when to reduce humidity or get treatment.

Fast, wriggling run when lights go on
Typical silverfish behaviour; they avoid light. Often seen at night in bathrooms or kitchens.
Damage to paper or book edges
Notching, yellowing, or irregular feeding on edges. Indicates feeding on starch and cellulose.
Holes or stains on fabrics
Natural fibres (cotton, linen) and starched items can be damaged. Check stored clothing and linens.
Shed scales or faecal pellets
Tiny scales or dark pellets in cupboards or drawers. Confirms presence even if you rarely see the insects.
Silverfish in warm spots only
Likely firebrat. Check near boilers, hot pipes, or attics; treat and reduce harbourage.
Single sighting vs many
One may be a stray; repeated sightings or damage suggest a population. Get help if it persists.

When to get professional help

Silverfish in multiple rooms or recurring after cleaning
Visible damage to books, documents, wallpaper, or fabrics
High numbers in bathrooms, cupboards, or storage
Firebrats near boilers or in commercial premises
You have reduced humidity but still see activity
You need targeted treatment of cracks, voids, and hiding places

Call Get silverfish control

Ready to tackle silverfish?

We target hiding places and advise on humidity control for long-term results.

Get a quote Silverfish control

Silverfish Identification Guide

Identify silverfish (fishmoth) and firebrat. Know where they hide, what damage to look for, and when to get help.

How to use this guide

Check shape and colour — teardrop-shaped, silvery-grey = common silverfish; mottled brown/grey = firebrat.

Note size — adults about 12–19 mm; three long tail bristles at the rear.

Note where you found them — bathroom, basement, cupboard, or near heat (firebrat prefers warm spots).

Look for damage — yellowing or notching on paper, books, wallpaper; holes or stains on fabrics.

Rule out lookalikes — earwigs have pincers; booklice are smaller and different shape; silverfish have no wings.

Then match to the species card using the quick comparison table; reduce humidity and treat hiding places.

Quick comparison

Silverfish / type	Colour	Size	Commonly found	Key clue
Common silverfish (fishmoth)	Silvery-grey; metallic sheen	~12–19 mm	Bathrooms, basements, cupboards; dark, humid	Fast, wriggling run; three tail bristles; nocturnal
Firebrat	Mottled grey, brown, tan	~12–15 mm	Near boilers, hot pipes, attics; warm areas	Prefers heat; similar shape to silverfish; three tail bristles
Grey silverfish	Grey; less metallic	Similar to common silverfish	Damp rooms, kitchens, bathrooms	Same habits; damage to paper and starch

Common signs by location

Where you find silverfish — bathroom, cupboard, or near heat — points to the type and the right control. Reduce humidity and treat hiding places.

Bathroom or kitchen

High humidity attracts silverfish. Check under sinks, behind cabinets, and in corners. Reduce moisture and fix leaks.

Common silverfishGrey silverfish

Cupboards and bookshelves

Damage to paper, book bindings, or cardboard; small faecal pellets or shed scales. Store paper in dry, sealed containers.

Common silverfish

Basement or storage

Dark, damp storage is ideal. Dehumidify and reduce clutter; inspect boxes and books for damage.

Common silverfish

Near boilers or hot pipes

Firebrats prefer warmth. Seal gaps and reduce harbourage; treat if numbers are high.

Firebrat

Behind wallpaper

They feed on paste and paper. Peeling or damaged wallpaper can hide silverfish; treat wall voids and reduce humidity.

Common silverfish

Why silverfish keep coming back

Humidity remains high — bathrooms, leaks, or poor ventilation keep conditions ideal.

Food sources available — paper, cardboard, starch-based glue, and fabrics in cupboards.

Hiding places not treated — cracks, voids, and clutter provide refuge.

New items brought in — second-hand books or stored goods can introduce or re-introduce them.

No long-term moisture control — treatment without reducing humidity often leads to return.

Adjacent areas still infested — silverfish can move between rooms or from neighbouring units.

Common silverfish signs and behaviour

These patterns help you confirm identification and know when to reduce humidity or get treatment.

Fast, wriggling run when lights go on

Typical silverfish behaviour; they avoid light. Often seen at night in bathrooms or kitchens.

Damage to paper or book edges

Notching, yellowing, or irregular feeding on edges. Indicates feeding on starch and cellulose.

Holes or stains on fabrics

Natural fibres (cotton, linen) and starched items can be damaged. Check stored clothing and linens.

Shed scales or faecal pellets

Tiny scales or dark pellets in cupboards or drawers. Confirms presence even if you rarely see the insects.

Silverfish in warm spots only

Likely firebrat. Check near boilers, hot pipes, or attics; treat and reduce harbourage.

Single sighting vs many

One may be a stray; repeated sightings or damage suggest a population. Get help if it persists.

When to get professional help

Silverfish in multiple rooms or recurring after cleaning

Visible damage to books, documents, wallpaper, or fabrics

High numbers in bathrooms, cupboards, or storage

Firebrats near boilers or in commercial premises

You have reduced humidity but still see activity

You need targeted treatment of cracks, voids, and hiding places

Silverfish Identification Guide

How to use this guide

Quick comparison

Species at a glance

Appearance

Commonly found

Behaviour

Why you may be seeing them

Often confused with

When to get help

Appearance

Commonly found

Behaviour

Why you may be seeing them

Often confused with

When to get help

Common signs by location

Bathroom or kitchen

Cupboards and bookshelves

Basement or storage

Near boilers or hot pipes

Behind wallpaper

Why silverfish keep coming back

Common silverfish signs and behaviour

Fast, wriggling run when lights go on

Damage to paper or book edges

Holes or stains on fabrics

Shed scales or faecal pellets

Silverfish in warm spots only

Single sighting vs many

When to get professional help

Related pages

Ready to tackle silverfish?

Silverfish Identification Guide

How to use this guide

Quick comparison

Species at a glance

Appearance

Commonly found

Behaviour

Why you may be seeing them

Often confused with

When to get help

Appearance

Commonly found

Behaviour

Why you may be seeing them

Often confused with

When to get help

Common signs by location

Bathroom or kitchen

Cupboards and bookshelves

Basement or storage

Near boilers or hot pipes

Behind wallpaper

Why silverfish keep coming back

Common silverfish signs and behaviour

Fast, wriggling run when lights go on

Damage to paper or book edges

Holes or stains on fabrics

Shed scales or faecal pellets

Silverfish in warm spots only

Single sighting vs many

When to get professional help

Related pages

Ready to tackle silverfish?