9) * Oreochromis aureus (Steindachner, 1864);

Cichlidae.

Blue Tilapia; Tilapia, Tilapia Azul (Fig. 3C).

Diagnosis: This exotic species differs from the other species of the family occurring in the freshwaters of the country by having three anal spines [vs. four or more in the other species, except Oreochromis niloticus (Linnaeus, 1758) and Andinoacara coeruleopunctatus (Kner, 1863)]. From these, it differs by the following combination of characters: absence of iridiscent light blue-green spots and lines on the head and the anterior portion of the body (vs. present in A. coeruleopunctatus); gill-rakers 18–26 (vs. 9–12 in A. coeruleopunctatus and 27–33 in O. niloticus); dorsal fin spines 15–16 (vs. 13–14 in A. coeruleopunctatus and 16–18 in O. niloticus); absence of dark vertical stripes on the caudal fin (vs. present in O. niloticus).

Basis of the record: A single specimen was collected in the río Pacuar (Térraba River basin), 4 km SE of San Isidro del General, under bridge on road San Isidro-Dominical, San José (09.35264, -83.72790), at 619 m. a.s.l., on March 25, 2013 by Carlos Garita (UCR 3018-001).

Remarks: This species was introduced to the country by government agencies and private entities in an attempt to strengthen aquaculture activities. It is possible that this species is widely distributed in the country.