Pterophyllum scalare, the Scalare or Angelfish comes from the Rio Negro and Amazon basins and attains a length of 5 inches. Their unusual shape, graceful movement and attractive coloring make the Angelfish one of the perennial favorites among aquarists. The body is compressed. Body color is silvery. The iris of the eye is red, and a black vertical bar passes through the eye to the base of the gill-plate. A second black bar descends from the first dorsal rays to the first anal rays, and a heavier bar descends from the middle rays of these fins, extending well into both. There is another bar at the caudal base and some faint ones cross the rail fin itself. The top and bottom rays of the tail are elongated into threadlike filaments. The fins are the unusual feature; the dorsal fin is almost as high as the body is deep and is rounded on top. The anal fin is even deeper than the dorsal is high, and the first ray also forms a long filament which extends beyond the tail. The ventral fins consist of only a few rays, which in some specimens are longer than the overall size of the fish. Sexes are very difficult to distinguish. Careful observation, however, will disclose that the female has a larger vent. The female's tube has about twice the diameter of the male's.