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Spotted Scat

Scatophagus argus

Brackish Indo-Pacific

A round, disc-like shoaling fish marked with dark spots. Although juveniles tolerate freshwater temporarily, long-term survival demands brackish conditions progressing to full marine salinity as adults. They possess mildly venomous dorsal spines, devour aquatic vegetation indiscriminately, and produce heavy waste, requiring diligent filtration and strong water flow.

Also called: Spotted scat, Argus fish, Butter fish.

25 cm adult length, drawn to scale. round body.

Outgrows a typical home tank. Check this fish against the adult size above before buying a juvenile. The minimum shown is the least it is kept in for good, not a comfortable size.
Brackish species. Needs a little salt in the water, below full marine strength. It will not mix with most freshwater fish.

Try it in the planner Opens a tank sized to its minimum with 4 fish added.

What it needs

ItemValueBecause
Adult length 25 cm Used for the Space check: the tank must be long enough for the fish to turn round.
Smallest tank 400 L, at least 150 cm long estimated The least water and floor length this species is kept in for good, as a single fish or smallest group.
Extra water per added fish 80 L estimated What each further fish adds once the minimum is met.
Waste load Class 4 of 5 estimated How much waste an adult makes against its size. Feeds the Load check.
Temperature 22 to 28 C Stock sharing a tank need overlapping ranges.
pH 7.5 to 8.5 Compared with tankmates in the Water check.
Hardness GH 12 to 25, KH 8 to 15 Degrees of general and carbonate hardness.
Flow Medium Low-flow fish are stressed in a strong current.
Light Moderate Matched to the lighting class on the needs sheet.
Group size At least 4, ideally 6 Kept alone or in small numbers it hides, fades or turns on tankmates.
Temperament Peaceful Not territorial.
Swims in Middle water Fish that use different levels share a tank more easily.
Lifespan About 12 years A fish is a long commitment.
Experience Some experience helps A guide to how forgiving the species is of mistakes.

Tags marked estimated are judged from the size and habits of the species rather than measured, so treat them as a sensible default.

Diet and tank layout

Spotted Scat is an omnivore that swims in the middle of the tank. It eats or uproots plants, so choose hard-leaved species or none. Give it some cover. It nips fins.

Tankmates

Compare any two fish on the compatibility page, or print the equipment for a stock on the needs sheet. How this is worked out: the method.