Spotted Scat

Argus Fish, Red Scat, Green Scat

Family: Scatophagidae Spotted Scat, Scatophagus argus, Argus Fish, Red Scat, Green ScatScatophagus argusPhoto © Animal-World: Courtesy Ken Childs
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I Hv 4 green scat at the momment. Caught them wen they were about 1mm in size. Head was red as juveniles which disappear at about 1/2 inches in size. They are now... (more)  BK Tee

The Spotted Scat is one of the friendliest and most popular brackish water fish available!

The Spotted Scat Scatophagus argus is an extremely attractive fish with a silvery or bronze case and covered with spots. With two color versions of the Spotted Scat, the Red Scat and the Green Scat, this fish has a lot to offer. The Green Scat is the type most commonly seen. The Ruby Scat or Red Scat is a red subspecies. Scatophagus argus arromaculatus, is generally more expensive but is well worth searching out. A few of the other names they are know by include Argus Fish, Common Scat , and Leopard Scat.

The genus name of Scatophagus means "offal-eater' or ‘excrement eater’ and is used because of their habit of living near floating toilets in Southeast Asia and eating anything that shows up. It hasn't been determined if they actually eat what comes out of the pipes, or if they are drawn to the smaller life that feeds on this. Still it’s fortunate that this type of ‘food’ is not necessary to keep them in good condition!

The Spotted Scat, along with the Mono Fish and Archerfish is one of the quintessential brackish water fish. These are all big, attractively patterned, and very durable fish. Almost every brackish aquarium will include at least one these types. The Spotted Scat is a bit larger brackish fish than either of those other two, typically reaching 6 - 8 inches (15-20 cm) in the aquarium. They generally get along well with all types of large fish except for aggressive species. Small fish too, as long as they are too big to be eaten.

Argus Fish are peaceful schooling fish, and a mixed school of Scats and Monos can be kept with great success. But the Scats are more curious, independent, and outgoing than the Mono fish. They have very hearty appetites and will greedily eat anything that comes their way. They will quickly become quite friendly and tame. But be very careful when handling scats. The spines on their fins are mildly venomous and it hurts if you are unlucky enough to get stuck by one.

If they are handled correctly, the Spotted Scats are a fish that is equally at home in freshwater or saltwater or anywhere in between. In nature their lives are usually spent in the mouths of rivers where the salinity of the water is constantly changing. Although they will do great in a saltwater aquarium, they are not usually considered for this use because their colors are not bright enough.

For more Information on keeping this fish see:
Guide to a Happy, Healthy Freshwater Aquarium

  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Perciformes
  • Family: Scatophagidae
  • Genus: Scatophagus
  • Species: argus
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Spotted Scat - Quick Aquarium Care
  • Aquarist Experience Level: Advanced
  • Size of fish - inches: 15.0 inches (38.10 cm)
  • Minimum Tank Size: 60 gal (227 L)
  • Temperament: Semi-aggressive
  • Aquarium Hardiness: Moderately hardy
  • Temperature: 68.0 to 82.0° F (20.0 to 27.8° C)
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Habitat: Distribution / Background

The Spotted Scat Scatophagus argus was described by Linnaeus in 1766. The species has a very large distribution, they are common throughout the Indo-Pacific region. Most seen for sale have been collected in or near Thailand. Other names this fish is commonly known by are Argus Fish, Red Scat, Green Scat, Ruby Scat, Argusfish, Common scat, Leopard scat, Butter fish, Spotted Butt, Spotted Butterfish, Spotted Butter Fish, Spotted Scad, and Spadefish.

The Ruby Scat or Red Scat is considered a subspecies, Scatophagus argus arromaculatus (Syn: Scatophagus 'rubifrons'). It is found only in Sri Lanka, New Guinea, and Australia. The Spotted Scat species are listed on the IUCN Red List as least concern (LC) due to their wide distribution, resiliency, and adaptability.

Argus Fish normally inhabit brackish estuaries, freshwater streams, mangroves, and natural embankments. These fish start their lives out in freshwater and move to saltwater as they mature. They feed on worms, crustaceans, insects and plant matter.

  • Scientific Name: Scatophagus argus
  • Social Grouping: Groups
  • IUCN Red List: LC - Least Concern


The Argus Fish or Spotted Scat has a strongly compress, squarish body with a steeply slanted profile to the head. Argusfish can reach up to 15 inches (38 cm) in the wild. In the aquarium they will typically reach about 6 - 8 inches (15-20 cm) in the aquarium with a life span of about 20 years.

The body coloration of the Common Scat or Green Scat is a shiny silver with a light greenish cast. The Red Scat is similar but with a reddish cast to it that is especially notable dorsally along its back and on the fins. True to its name, there are black spots all across its body, extending onto the fins. In mature adults the spots can be faded, often only visible on the upper parts of its sides and back.

Juveniles are more rounded in shape, getting more rectangle in shape as they mature. In color the Green Scat juvenile is brown or green with the leopard like spots and usually some stripes on the head. As they mature the stripes fade and the body color becomes more bronze or silvery. The Red Scat or Ruby Scat juvenile has the same body shape as the Green Scat, but is more brilliantly colored with bright red or orange on the dorsal fin.

  • Size of fish - inches: 15.0 inches (38.10 cm) - Typically reach about 6 - 8 inches (15-20 cm) in the aquarium.
  • Lifespan: 20 years

Fish Keeping Difficulty

The Spotted Scat is suggested for a more experienced fish keeper. When young these fish live in freshwater and as they age need to be moved slowly into a brackish/ salt environment. Managing the proper salt amounts can be difficult and will be an added expense over a traditional freshwater fish. These types of changes can be difficult to do properly. These fish also grow very large which makes a need for larger tanks as they grow. The Spotted Scat also has venom in small spikes that can cause great pain, so caution needs to be taken during tank maintenance.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Advanced - These fish have changing water conditions as they age.

Foods and Feeding

The Argus Fish is an omnivorous species. In the wild they feed on a variety of plant matter along with worms, crustaceans, and insects. In captivity feeding is no problem since they will eat virtually anything considered as aquarium fish food. They have very hearty appetites and will greedily eat anything that comes their way.

The Argusfish are distinctly more herbivorous than many others. They need a good amount of vegetable foods and they will munch on aquarium plants. As with any fish, a varied diet is important so be sure to feed dried, frozen and fresh foods. Flakes or pellets that contain algae and vegetable matter are suggested. They can also be offered vegetable matter such as algae, dried seaweed, blanched lettuce and spinach, thin slices of cucumber or zucchini, and frozen peas.

  • Diet Type: Omnivore - They are not picky eaters. Should be fed a mainly vegetable based diet with the occasional meaty food offered.
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Most of Diet - Dried Seaweed, lettuce, quality flake food.
  • Meaty Food: Some of Diet - Brine shrimp, krill, mysis shrimp, and blood worms.
  • Feeding Frequency: Daily

Aquarium Care

Scats are very messy fish due to their eating habits, so a strong filtration system will be needed. As they age these fish require additional salt added to their water. Make sure to add salt with every water change. Their tank should be cleaned weekly and about a 30% water change done. Be very careful when handling scats. The spines on their fins are mildly venomous and it hurts if you are unlucky enough to get stuck by one. An injury can be treated by soaking it in hot water.

  • Water Changes: Weekly - Do about a 30% water change weekly, with salt added as they age.

Aquarium Setup

Argusfish will swim in all parts of the aquarium but will most likely spend most of their time near the middle. The Spotted Scat can get quite large so a tank of at least 60 gallons should be provided to begin with. If you do a good job and keep one in good shape, a larger tank will be eventually needed. A 9 to 15 inch fish is large but when it is shaped like a scat, it's really large! Just imagine a dinner plate with fins and you'll get the idea. Odds are that a tank raised specimen will never grow to full size, but even a salad plate with fins is big.

Some advanced aquarists are able to keep scats in freshwater. However they really do better if kept in full saltwater or brackish water made with a good marine saltwater mix. Add approximately 2 - 3 teaspoons per gallon. They are very sensitive to nitrites, so make sure you have good biological filtration.

For substrate use a fine gravel or sand. An efficient canister filter will work well with these aggressive, messy eaters. Spotted Scats need plenty of swimming space. Driftwood, branches and roots make good decor and an area for the fish to entertain themselves. Because they are avid feeders on vegetable matter, plants don't really work in the Argus Fish aquarium.

  • Minimum Tank Size: 60 gal (227 L) - Will need a bigger tank as they grow.
  • Suitable for Nano Tank: No
  • Substrate Type: Sand/Gravel Mix
  • Lighting Needs: Moderate - normal lighting
  • Temperature: 68.0 to 82.0° F (20.0 to 27.8° C)
  • Range ph: 7.5-8.5
  • Hardness Range: 12 - 18 dGH
  • Brackish: Yes - Young fish do well in freshwater and as they age will need to move to brackish.
  • Water Movement: Moderate - Scats will swim in all parts of the aquarium but will most likely spend most of their time near the middle.
  • Water Region: All

Social Behaviors

They are a peaceful species that do best in groups of at least four. A mixed school of Scats and Monos can be kept with great success. Argus Fish generally get along well with all types of large fish except for aggressive species. They will not bother other fish unless those fish are small enough to be considered a meal.

Spotted Scats are very lively fish that are curious and outgoing, They will heartily eat anything you offer and soon become tame pets, and of course they may also eat any plants in the tank. Be careful when feeding or cleaning the tank, because the spines on their fins are mildly venomous and it can be painful if you get stuck.

  • Venomous: Yes - Spines are mildly venomous.
  • Temperament: Semi-aggressive
  • Compatible with:
    • Same species - conspecifics: Yes - Groups of 4 or more are suggested.
    • Peaceful fish (): Monitor - They will eat smaller fish.
    • Semi-Aggressive (): Monitor
    • Aggressive (): Threat
    • Large Semi-Aggressive (): Monitor
    • Large Aggressive, Predatory (): Threat
    • Slow Swimmers & Eaters (): Monitor
    • Shrimps, Crabs, Snails: May be aggressive
    • Plants: Threat - They will most likely eat any plants in the aquarium.

Sex: Sexual differences

Sexual differences are unknown.

Breeding / Reproduction

This Spotted Scat has never been bred in captivity. These fish normally spawn in saltwater reefs and the fry will swim to freshwater to grow and then return to a more brackish/ salt environment. This would be very hard to replicate in captivity Scatophagus species rarely, if ever, spawn in the aquarium.

  • Ease of Breeding: Difficult

Fish Diseases

With the Scats disease is not usually a problem in a well maintained aquarium. That being said there is no guarantee that you won't have to deal with health problems or disease. Anything you add to your tank can bring disease to your tank. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance. Banded Archer are very resilient once established in a tank.

A good thing about the Scat is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your Scat the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish will is more likely to acquire disease.

Spotted Scats are fairly hardy fish if their water requirements are met, but are subject to the same diseases as other tropical fish. One of the most common freshwater fish ailments is ich. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.


Argus Fish or Spotted Scats are easy to find. Both the Red Scat or Ruby Scat, and Green Scat are commonly available. The price of the red version is usually quite a bit higher than that of the green.


Author: Ken Childs, Clarice Brough CFS, Jeremy Roche
Lastest Animal Stories on Spotted Scat

BK Tee - 2015-12-07
I Hv 4 green scat at the momment. Caught them wen they were about 1mm in size. Head was red as juveniles which disappear at about 1/2 inches in size. They are now about 2.5 inches in size. I would really like to know if they eat corals as well. read in an article that they are great Atapsia eaters but worries they eat other corals as well.Appreciate if anyone hv this experience as one of my marine tank is blooming with Atapsia.

Balvindersingh Suacharia - 2015-08-08
I want to buy scat fish..  All indifferent colours. 

Im from india.  Plz mail me. 

mitch - 2012-12-06
Can they be added to salt water tanks? I was told to get one to eat the aiptasia so if yes do you just dump them intop the salt water from fresh water?

  • Jeremy Roche - 2012-12-07
    They can slowly be brought into to salt water as they mature.  Start by addind a little at a time.  Make sure to test the salinity, keeping levels from moving too fast or getting too high ang shocking the fish.  I wouldn't just dump it it.  Mixing it in the water during water changes.
  • Donny Tantono - 2014-05-10
    I sell spotted scat fish from indonesia. You can send me an email.
FendiSunny - 2014-01-18
I currently have 2 Green and 1 Red Scat in my 5 feet tank. They're in freshwater tank with aquarium salt not sea salt. Been keeping them with parrot fish whom the salt is intended for. The Scats are around 3-4 years old. Size is about 4-5 inches. The Green ones seems to grow nicer as adults then the red ones. I also realise the red ones grow way faster than the green ones. They are easy to feed and these 3 are always schooling together. So far I'm not sure when to start moving them to brackish cause they're still fine and growing in the tank. So far so good.

Balvindersingh Suacharia - 2015-08-08
I want to buy scat fish..  All indifferent colours. 

Im from india.  Plz mail me. 

Peta - 2012-06-03
I have a male and female green Scats, the make is approx 7 inches and the female approx 5 inches. They have been very easy to maintain and I find they love broccoli as a treat!! They are sociable and come to the top of the tank at feeding time!! I am looking at selling them if anyone is interested,

  • Shane - 2012-07-27
    You can not sex scats
  • Peta - 2012-08-24
    Ok thanks Shane,
  • dick humphrey - 2013-01-07
    I would like to know how you got a male in the first place. I had 2 scats for 4 years and then they died even though they seam healthy. This was because they were egg bound. Without a male that's what happens. I had a 50 gallon breeder tank fresh water always with Magnesium (epsom salt) (T for every 4 gal) and fed them just flake food they were find that way. These fish (the body bio) is freshwater. They they just can live in the other water (males are very hard to find anywhere other than fresh water) so how i have tried to order one.... Sorry I want a young one.