The Silver Mono, or Finger Fish, is a stunning, fast-moving schooling fish known for its shiny, diamond-shaped body. They are euryhaline; juveniles inhabit freshwater or brackish estuaries, but adults require high-end brackish or full marine setups to thrive. They are active, voracious eaters that must be kept in groups to curb fin-nipping and internal aggression.
Finger Fish At a Glance
Finger Fish Tank Requirements
Will Finger Fish fit in your tank?
Care guides tell you what Finger Fish needs, the next question is whether your tank can safely provide it. Test Finger Fish against your tank size, maintenance needs, and the fish you already keep before you buy.
Useful setup supplies
We may earn from qualifying purchases
Finger Fish Water Parameters
Water care products
We may earn from qualifying purchases
Finger Fish Temperament & Compatibility
Finger Fish Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Adult (Standard)
The adult form. Requires a very large aquarium with high-end brackish or full marine salinity. Deep-bodied and lightning-fast, they require plenty of unobstructed swimming space.
Same care requirements as the base species
Also known as: Adult Mono, Marine Mono
Juvenile (Grow-out)
Often sold at 5-10cm in purely freshwater setups. They are highly active and will outgrow standard tanks quickly. Owners must be prepared to gradually increase the salinity to brackish/marine as the fish matures to prevent immune system collapse.
Differs in 4 traits from base species
Also known as: Baby Mono, Freshwater Mono
Finger Fish Care Guide Summary
The Finger Fish, scientifically known as Monodactylus argenteus, belongs to the Oddballs family group. Adults reach a maximum size of approximately 25 cm and have a compressed body shape with a fast growth rate. Classified as semi-aggressive, this species primarily occupies the mid-level zone of the aquarium and produces a high level of biological waste.
To thrive, the Finger Fish requires a brackish required aquarium with a minimum volume of 470 litres and a tank length of at least 150 cm. Water temperature should be maintained between 24°C and 28°C, with a pH range of 7.5–8.5 and a general hardness of 12–30 dGH. A moderate water flow is preferred.
The Finger Fish is a rewarding species to keep, provided its core environmental needs are met. This species is available in 2 varieties: Adult (Standard) and Juvenile (Grow-out). Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Finger Fish Habitat Setup
When setting up an aquarium for the Finger Fish, a moderate water flow best suits their natural preferences. Because this species occupies the mid-level zone, the aquarium layout should prioritise open swimming space in the centre of the tank for free movement. Useful additions include smooth gravel or rounded substrate to protect their sensitive barbels. Keepers should note that live planted layouts may be difficult to maintain, as this species tends to uproot or consume vegetation.
Finger Fish Compatibility Notes
Classified as semi-aggressive, the Finger Fish is a social species that requires the company of its own kind to thrive. When choosing tankmates, avoid housing with slow-moving or long-finned species that may become targets for fin nipping, conspecific aggression can be intense, especially in smaller tanks, and their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the mid-level zone can help reduce competition and territorial overlap.
Finger Fish Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Finger Fish.
Feeding products
We may earn from qualifying purchases
.webp?2026-04-25T14%3A35%3A38.022Z)
Frequently Asked Questions About Finger Fish
How big does Finger Fish get?
Finger Fish (Monodactylus argenteus) typically reaches a maximum adult size of approximately 25 cm. They have a compressed body shape and a fast growth rate.
What tank size does Finger Fish need?
A minimum aquarium volume of 470 litres and a tank length of at least 150 cm are recommended for Finger Fish. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Finger Fish need?
Finger Fish thrives in brackish required conditions with a temperature range of 24–28°C, a pH between 7.5 and 8.5, and a general hardness of 12–30 dGH. A moderate water flow is preferred.
Is Finger Fish peaceful or aggressive?
Finger Fish is classified as semi-aggressive with an aggression score of 5 out of 10. They can work in community setups but may clash with certain tankmates.
Can Finger Fish live alone?
No, Finger Fish should be kept in groups of at least 5 to reduce stress and encourage natural behaviour.
Does Finger Fish have any special tank requirements?
Yes. Finger Fish benefits from smooth gravel (sensitive barbels) in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Plants That Suit Finger Fish
These plants pair well with Finger Fish based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Java Fern
Leptochilus pteropus
Jungle Val
Vallisneria americana
Lemon Bacopa
Bacopa caroliniana
Marimo Moss Ball
Aegagropila linnaei
Micro Sword
Lilaeopsis brasiliensis
Moneywort
Bacopa monnieri
Fish Similar to Finger Fish
Mono Sebae (Brackish)
Monodactylus sebae
A striking, deeply compressed (diamond-shaped) schooling fish native to the estuaries and mangroves of West Africa. While juveniles are frequently found in freshwater or light brackish water, adults strictly require high brackish to full marine conditions to survive long-term. They are hyperactive, grow extremely tall, and require massive, open aquariums to accommodate their schooling nature.
Silver Datnoid (Silver Tigerfish)
Datnioides polota
A striking predatory fish known for its deep body and tiger-like stripes. Unlike other Datnoids, the Silver Datnoid is euryhaline and naturally inhabits estuaries; while it can survive in freshwater, it thrives in light brackish conditions. They are ambush predators with highly protrusible jaws capable of swallowing surprisingly large prey.
Scarlet Badis
Dario dario
One of the smallest known aquarium fish, resembling a tiny jewel. Males display brilliant vertical red and iridescent blue stripes. While beautiful, they are known for being extremely picky eaters, often refusing dry foods and requiring live or frozen micro-foods (Daphnia, Baby Brine Shrimp). Males act like tiny Cichlids and will stake out territories.
Crimsonspotted Rainbowfish
Melanotaenia duboulayi
A highly active, schooling freshwater fish endemic to eastern Australia, often considered the original 'Australian Rainbowfish' in the aquarium trade. Recognizable by a prominent crimson red spot on the operculum (gill cover) and striking silvery-blue to greenish bodies. They are peaceful but extremely vigorous swimmers, requiring plenty of horizontal swimming space and a tight-fitting lid to prevent jumping.
White Cloud Mountain Minnow
Tanichthys albonubes
A hardy, peaceful, and active schooling fish famous for its ability to thrive in unheated, sub-tropical aquariums. Native to the mountain streams of China, they feature a bronze body with a striking neon-like lateral stripe and red-tipped fins. They are strictly schooling fish and must be kept in groups to feel secure and display their best colors.
Goldfish (Comet / Common)
Carassius auratus
One of the most commonly kept and misunderstood fish in the hobby. Single-tailed goldfish (Comets, Commons, Shubunkins) are fast-growing, highly active coldwater fish that produce enormous amounts of waste. They are best suited for ponds or massive aquariums. They will uproot plants, sift substrate constantly, and eat anything that fits in their mouths.