The blue-spotted spinefoot was first formally described in 1835 as Amphacanthus corallinus by the French zoologist Achille Valenciennes with the type localities given as the Seychelles and Java.

[6] The blue-spotted spinefoot has a deep and compressed body with a standard length which is around twice its depth.

Small juveniles have slender blue vertical lines on the flanks that break up into spots as they grow.

[1] Blue-spotted spinefoots school as juveniles in sea grass beds, moving into branching Acropora corals and beginning to form pairs as around 6 cm (2.4 in).

The juveniles browse epiphytic algae from the leaves of sea grasses while the adults prefer macroalgae.

The blue-spotted spinefoot spawning is governed by the water temperature and the lunar cycle, normally occurring at dusk.