Mono Fish Stats InfographicMono Fish, also known as Monodactylus argenteus and Mono argentus, belong to the Monodactylidae family. Their distribution is widespread. They can be found along the Australian coast, throughout Southeast Asia, and Eastern Africa. They are mainly found in the Red Sea.

These fish can mainly be found in the shallow parts of inshore reefs, freshwater tidal pools, and estuaries. If you’re an experienced aquarist, this fish species will be a perfect addition to your aquarium. These fish are schooling fish. You must keep them in groups.

Let us delve into the details about this fish species so that you can happily keep them in your aquarium!

Fundamental Mono Fish Stats

Before going to the details about how to take care of this fish species, it is important that you know some of the essential statistical information about the silver mono.

This information will form the basis of how well you can take care of these fish. The following table lists basic statistical information about this species of fish.

Size 6 inches
Tank capacity 55+ gallons
pH 7.2 – 8.5
Water temperature 75.0 to 82.0° F (23.9 to 27.8° C)
Hardness of water 8-14 dGH
Aquarium strata Top, middle and bottom dwellers (all strata)
Level of care High level of care

The following table lists the basic biological specifications of this species of fish. As an aquarist, you should know these to take complete care of your pets.

Scientific name Monodactylus argenteus
Common name Mono fish, silver moony, diamond fish, butter bream, silver moony fish
Origin The Red Sea (coastlines of Australia, Southeast Asia, and Eastern Africa)
Lifespan 7-10 years
Genus Monodactylus
Species M. argenteus
Family Monodactylidae
Diet Omnivorous diet

General facts about the Monodactylus argenteus

Mono fishThe Monodactylus argenteus is better kept by aquarists who are well experienced. You need to have a good amount of experience in housing fish to take care of this species properly.

To start off, let’s take a look at the general facts that you need to know about these fish to maintain them appropriately:

  • These fish have a flat, disc-shaped body.
  • In terms of size, in their natural habitat, they grow up to 10.6 to 11 inches. However, in fish tanks or aquariums, they will grow up to 6 inches.
  • You can expect these fish to live anywhere between 7-10 years.
  • They have an attractive appearance. They have silver-colored bodies. Their tail, anal, and dorsal fins are light yellow in color.
  • They also have two vertical stripes on their body, one through their eyes and the other just behind the first stripe. The second stripe extends across their bodies and touches the edges of their anal and dorsal fins.
  • Juvenile fish of this species can be differentiated from the adults based on the color of their dorsal fin. Juveniles have bright yellow dorsal fins.
  • These fish are found in the Red Sea. They are distributed along Australian coastlines, Southeast Asia and Eastern Africa.
  • In nature, they thrive in brackish waters. They mostly dwell in the upper strata of estuaries, tidal pools, and inshore reefs.
  • They are a schooling variety of fish. They thrive best in groups of 5 and more.
  • Sexual dimorphism is unknown. This means that there are no physical characteristics that provide a basis for distinguishing between male and female fish of this species.
  • In the aquarium, these fish need brackish water to thrive. Although they can live in freshwater, they won’t survive for long.
  • Try to keep your aquarium in an area that receives moderate to normal lighting.
  • These fish love swimming all over the aquarium. Given their size and activity level, opt for a large, rectangular tank.

Mono fish care

– General set-up

The Monodactylus argenteus is a high-maintenance species of fish. It is very important that you create the appropriate environment in their aquarium so that they can live up to 10 years. You need to be able to mimic the conditions of their natural habitat in the fish tank.

First and foremost, the size of the aquarium should be 55 gallons and above, because these fish are quite large in size. Also, they are schooling fish. So, you need to keep at least 5 of these fish in a tank so that they thrive. Therefore, you need to have a spacious aquarium.

These silver-colored pets are best housed by experienced aquarists. The Monodactylus argenteus needs brackish water to thrive. The water temperature should be ideally between 75.0 to 82.0° F (23.9 to 27.8° C). Keep the water hardness between 8-14 dGH and the pH level between 7.2-8.5.

To make the water brackish, add 2-3 teaspoons of marine water salt mix per gallon of water. Apart from this, you also need to have a good filtration system in place. They look their best when kept in pure saltwater.

These fish need high oxygen concentration in the aquarium. For this, you need an efficient under gravel filter. Sand or fine gravel is ideal as the substrate.

The silvery beauties are extremely active and enjoy swimming all around the aquarium. Add roots, branches, and driftwood to decorate the swimming space. This will keep the fish entertained.

These fish are messy eaters and generate a lot of waste. Therefore, the water must also be changed frequently along with a good filtration system in place. Make sure you can change at least 30% of the tank water every week.

– Diet

Feeding mono fish is fairly easy. This is because they follow an omnivorous diet. A point to note about these fish is their greedy nature. They consume a substantial amount of food which makes them fast-growing feeders.

In their natural habitat, these fish consume different varieties of plant matter, insects, and detritus. As mentioned earlier, these fish are relatively easy to feed. They are not fussy when it comes to their diet.

If you’re housing this species in your aquarium, you can feed them dried food. However, it’s important that you maintain a balance of frozen, dried, and fresh food. Variety is key for their survival.

You can feed them bloodworm, brine, and shrimps. These fish can also be fed vegetables and vegetable matter. You can give them blanched lettuce, boiled peas, blanched spinach, and algae.

To sum it up, this mono can be given flake food, pellets and tablets, a few meaty food options, a few fresh food options like shrimps, bloodworms, etc., and a few vegetables. Also, remember that this species prefers to be fed multiple times a day.

– Common illnesses to tackle

The best thing about these fish is the fact that they are fairly hardy by nature. They will stay healthy and live up to their life expectancy as long as you successfully maintain the water conditions. However, just as with any other fish species, you may encounter common diseases with this species as well.

In order to avoid the likelihood of your fish falling ill, you have to be careful about what you add to your aquarium. Be careful about adding tank mates, new substrate, decorations, and plants- all have the potential to carry bacteria. So, before you add any of the aforementioned objects or creatures, be sure to quarantine or clean them.

Owing to the hardy nature of the Monodactylus argenteus, you don’t have to be worried about a widespread outbreak of any fish disease. The outbreak is restricted to one or few fish. Just be on the lookout for any signs or symptoms so that you can detect the disease at an early stage.

The best way to tackle any kind of disease is by taking the correct preventative measures. You can prevent any disease outbreak by ensuring that your fish have a diverse diet. Not only that, try and provide ideal water conditions in terms of pH level, hardness, temperature, volume, etc. This will ensure that they remain happy and stress-free.

A fish that is prone to stress is prone to falling ill. These fish are prone to diseases that affect other tropical fish species. The most common illness for this particular fish species is Ich.

Ensure that the proper water conditions are maintained and healthy food is supplied. Just remember to be vigilant about any signs and symptoms. Check your fish routinely so that the disease can be tackled at an early stage.

– Breeding

Moony fishes haven’t been bred in aquariums or fish tanks. There is no information about successfully breeding them in captivity. This is not to say that there have been no reported incidents of spawning in fish tanks or aquariums. There are only a handful of reports about this species spawning in captivity.

However, as specified, these are all accidental cases. This spawning behavior has not successfully been recreated or duplicated. Therefore, it can be said that this species is difficult to breed. The difficulty of breeding is high.

In the context of breeding, another significant point worth noting is that the female and male fish cannot be differentiated. There are no unique physical characteristics that separate male and female fish of this species. Therefore, sexual dimorphism is unknown.

– Tank mates

The silver moonyfish is a schooling variety. This means that they need to be housed in an aquarium in groups of 5 or more. So, before you introduce any other tank mates into the aquarium, be sure to keep a minimum of 5 fish of this species.

Coming to tank mates, it is first important to understand the temperament of this fish species. These fish can be categorized as semi-aggressive. They are relatively peaceful. They do get aggressive with their own kind, so it is important to keep this species in groups of 5 and more.

If you try keeping these fish in trios or duos, they might not get a sufficient outlet for their aggression. Another interesting fact about this species is that they have a hierarchy. The largest fish is the leader and thus, dominant. The largest fish gets to feed first.

They can also be peaceful tank mates for other fish species. But you need to be careful about certain things. Don’t keep small fish, shrimps, crabs, or snails because these fish might eat them.

You should also not keep larger semi-aggressive or aggressive species of fish because this mono species will feel threatened. Be sure to never keep Angelfish and Monodactylus argenteus in the same tank. The mono ones try to clean off the two feelers that Angelfish have.

Ideal tank mates for this species would be Scats, Archerfish, Gobies (only brackish species), and larger Mollies. You can also keep plants in the aquarium. Do not keep any venomous or predatory fish species in the tank.


Now that we’ve covered all the details you need to know to house diamond fish, let’s take another look at some of the important facts related to their diet, care, breeding, and more:

  • Mono fish also known as monodactylus argenteus and mono argentusThese fish need brackish water to survive. They can be kept in fresh water for a short period of time but not for long periods of time.
  • A good filtration system is vital along with plenty of aeration. Change at least 30% of the tank water on a weekly basis.
  • It is easy to feed these fish because of their omnivorous diet. Provide a varied and balanced diet consisting of vegetable matter, flake foods, pellets or tablets, worms, brine shrimps, and prawns.
  • These fish are quite hardy by nature. Disease outbreaks can be controlled and treated if caught in the early stages. One of the main diseases to look out for is Ich.
  • The difficulty level of breeding these fish is very high. They cannot be spawned in captivity.
  • They have a peaceful yet playful temperament and have been categorized as semi-aggressive. Ideal tank mates for this species would be Scats, Archerfish, Gobies (only brackish species), and larger Mollies. Do not keep Angelfish with this fish species.

If you’re an experienced aquarist, this fish species can be a wonderful addition to your aquarium!

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