Not furry, but we like them anyway.
Silver Moony
Monodactylus argenteus
Also called Silver moonyfish, Mono, Natal moony, Butter bream, Diamondfish
From Indo-West Pacific, from the Red Sea, Persian Gulf and East Africa to Samoa, north to the Ryukyus and south to New Caledonia and Australia, in bays, mangrove estuaries, tidal creeks and lower river reaches12
A friendly guide, not veterinary advice. For anything about your pet's health, ask your vet.
At a glance the quick version
Looks how to spot one
Deep, disc-shaped scaled fish
A tall, almost diamond-shaped fish with a flat body and long, swept-back dorsal and anal fins. Adults are a bright mirror silver with yellowish fin edges and dark tips on the dorsal and anal fins. Juveniles are more yellow and have two dark vertical bars, one through the eye and one just behind the gill cover.2
Personality what they are like
An active, sociable fish that is often seen in large schools. It can be a little territorial, but in a group it is busy and outgoing.12
Daily activity how busy a day looks
A fast, mid-water swimmer that needs plenty of open swimming space for the group to move together.12
Grooming and care the hands-on bits
A tropical fish for about 24 to 28 C. Young fish are found in fresher water while adults favour brackish to marine water, so salinity is usually raised as the fish grow; adults can be kept in full saltwater aquaria.12
Home where they are happiest
A tropical estuary fish that lives in bays, mangroves and tidal creeks and grows to between 12 and 27 cm. A roomy tank with plenty of open water suits a schooling fish of this size, and adults can be kept in saltwater aquaria.12
Food basics what goes in the bowl
Feeds on plankton and detritus in the wild, so it does well on a varied mix of small foods offered in modest portions.12
Company who they like around
Best kept in a group, as it naturally forms schools. Seriously Fish lists monos among good companions for archerfish in a brackish tank.13
The story where it all began
Carl Linnaeus described the silver moony in 1758. Its species name argenteus is Latin for 'silvery'. It is taken in small local fisheries and has a long history in the aquarium trade, where it is known simply as the mono.21
Fun facts for the dinner table
- 1
It can live in fresh, brackish and sea water, which makes it a model species for research on salinity tolerance.2
- 2
Juveniles usually live in fresh water and move to saltier water as adults.1
- 3
Its species name argenteus comes from the Latin for silvery.2
- 4
It is common enough in Australian harbours and estuaries to be a familiar sight there.2
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 2016)1
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Silver Moony. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Salinity checkBrackish fish need a little marine salt, and some need more as they growevery week
- Water changeAbout 25% of the water, mixed to the same salinityevery week
- Water testevery week
- Filter rinseRinse in old tank water, never tap waterevery month
Owner questions the things everyone asks
How often should I feed my Silver Moony?
Feed your Silver Moony small amounts once or twice a day. Offer a varied mix of small foods like plankton and detritus, and avoid overfeeding to keep the water clean.12 Furry Diary plan
What does a Silver Moony eat, and what should it never eat?
In the wild it eats plankton and detritus, so a varied mix of small foods works well. For foods to avoid, it's best to ask a vet or a good breeder, as specific harmful foods aren't listed here.12
How much space does a Silver Moony need?
A roomy tank with plenty of open swimming space is essential for this active schooling fish. Since it grows up to 27 cm, the exact tank size depends on your group size, ask a good breeder for a recommendation.12
What temperature, light or water does a Silver Moony need?
Keep the water temperature between 24 and 28°C. Young fish prefer fresher water, while adults need brackish to marine conditions, raise salinity gradually. Furry Diary's plan suggests daily temperature checks and weekly salinity tests.12 Furry Diary plan
How often should I clean a Silver Moony's home?
Change about 25% of the water every week, mixed to the same salinity. Rinse the filter in old tank water once a month, never use tap water on it. Furry Diary plan
Can a Silver Moony live with others?
Yes, it's a sociable fish that does best in a school. It can be a little territorial, but in a group it's busy and outgoing. Good tankmates include archerfish in a brackish setup.123
How long does a Silver Moony live?
Lifespan varies depending on care and environment. For a typical range, please ask a vet or an experienced breeder.
Can I handle a Silver Moony?
Handling is not recommended, these fish are delicate and easily stressed. Enjoy watching them swim in their tank, and if you need to move one, consult a vet for safe methods.
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Furry Diary's own starting care plan. A friendly guide, not a vet's advice.
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- FishBase: Monodactylus argenteus, Silver moony fishbase.seused for size, environment, temperature, distribution, IUCN status, diet, schooling
- Wikipedia: Monodactylus argenteus en.wikipedia.orgused for other names, appearance, salinity tolerance, aquarium note, etymology, fun facts
- Seriously Fish: Toxotes jaculatrix seriouslyfish.comused for compatibility of archerfish with monos
- VCA Animal Hospitals: Feeding times and frequency for your dog vcahospitals.comused for owner questions
- ASPCA: Dog grooming tips aspca.orgused for owner questions
- ASPCA: Cat grooming tips aspca.orgused for owner questions
- ASPCA: People foods to avoid feeding your pets aspca.orgused for owner questions
- RSPCA: What to feed your rabbit rspca.org.ukused for owner questions
Checked 2026-09-30. Text is written in our own words from these sources.