The general colour of the species in this genus varies, as at night they take on a deeper colour than during daytime, and, as with all toadfishes and puffers, the colour of skin changes slightly depending on the mood or stress level of the animal. e.g When the Tetractenos is in oxygen-depleted water, it's underbelly will be a darker colour than the usual whitish-cream. The body of both species is covered in small, gravel-like pustules (spots). Small, sandpaper-like spines can be found on the body, and when the animal "puffs up" they stick out and make it feel even more rough.
Althugh the colour varies, T. hamiltoni, the more northern species (although the ranges of the two overlap) has clear, slightly cloudy fins, whereas the fins of a content T. glaber are bright orange-red. T. glaber also usually has finer pustules on its body.