TankBud

Silver mono

Monodactylus argenteus

Also known as Silver moony, Mono argentus, Fingerfish, Malayan angel

BrackishSaltwaterFish

Silver mono (Monodactylus argenteus)
Lawrencekhoo · CC BY-SA 4.0

Care at a glance

Temperature
75–82°F
24–28°C
pH
7.5–8.5
Adult size
9.8 in
25 cm
Minimum tank
159 gal
600 L
Temperament
Mostly peaceful
Social behavior
Schooling
Swim level
Middle
Diet
Omnivore
Difficulty
Difficult
Breeding
Hard
Rarity
Common
Reef safe
Not reef safe
Family
Monodactylidae
Origin
Indo-Pacific coastal waters, estuaries, and mangroves from East Africa to the western Pacific

Overview

The silver mono is a fast, mostly peaceful schooling fish for a large brackish tank. It suits experienced keepers rather than beginners.

Did you know

The silver mono is one of the classic estuary fish that walks the line between fresh, brackish and marine water over a single lifetime. Shops often sell tiny juveniles sitting in nearly fresh water, which makes them look like an easy community fish.

Caring for the silver mono

Keep silver monos in a shoal of at least five or six. Lone or paired monos turn skittish and nippy, and a proper group settles them down.

That group of large, active fish needs a big, open, well-filtered tank of at least 159 gal (600 L) with a long footprint. These are fast, deep-bodied swimmers that use the middle and upper water column, so length and volume matter more than decor.

Hold the water alkaline, hard and mineral-rich, at 75 to 82°F (24 to 28°C) and a pH of 7.5 to 8.5. Silver monos are euryhaline, meaning they handle a wide salinity range. They do not stay in fresh water long-term, though, the way the trade sometimes implies.

Their salt requirement climbs as they age. Small juveniles do fine in low-end brackish water around 1.005 to 1.010 specific gravity. Adults want high brackish to near-marine water, roughly 1.018 and up, so plan for a system that can hold marine-grade salinity. Raise the salinity gradually as they grow rather than in sudden jumps.

Feed them as omnivores, with a mix of meaty frozen foods and plenty of greens, since a diet poor in vegetables causes problems over time. Silver monos are mostly peaceful, but adults get pushy and nip slower or smaller tank mates. Pair them only with robust brackish company such as scats, archers and larger brackish gobies. They spawn pelagically in the wild, and spawning effectively does not happen in home aquaria.

Good to know

The silver mono is a deep, disc-shaped fish in the family Monodactylidae. Nearly all silver monos in the trade are wild-caught estuarine juveniles. It also goes by the names silver moony, fingerfish, Malayan angel and Mono argentus.

In the wild

Silver monos live in coastal estuaries, harbors and mangrove creeks across the Indo-Pacific, from East Africa to the western Pacific. There the salinity rises and falls with the tide.

Weekly picks

Tank mates

The silver mono is a mostly peaceful, schooling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a silver mono need?

A silver mono needs at least 159 gal (600 L). It spends most of its time in the middle.

What temperature and pH does a silver mono need?

A silver mono is comfortable at 75–82°F (24–28°C) with a pH of 7.5–8.5.

What does a silver mono eat?

A silver mono is an omnivore. Feed it a mix of meaty frozen foods and plenty of greens, since a diet poor in vegetables causes problems over time.

How big does a silver mono get?

An adult silver mono reaches about 9.8 in (25 cm).

Does a silver mono need a group?

Yes. A silver mono is a schooling species and should be kept in a group, not singly.

How does a silver mono breed?

A silver mono spawns pelagically in the wild. It effectively never spawns in home aquaria.

Related species