Apistogramma macmasteri is a widespread species of apisto with a large variety of localized and man-made colour forms. There are also many similar species that may be misidentified as A. macmasteri; on the flip side, various morphs and locales of macmasteri are often sold as other species, especially A. viejita (true viejita is basically unheard of in the hobby). They are an average sized apisto with males approaching 3 in max length; females stay smaller, around 2. Like most apistos they do well with various peaceful schooling fishes, and are usually more outgoing when some are present.

These are specimens of the line-bred Red Mask morph; they are currently about 1-1.5 long. The Red Mask line has very intense red colour covering almost the entire front half of the body in males; even females have more red pigment than usual. On top of that, males have blue streaking in the face, a silver back half of the body, and bold red and yellow finnage.