Hoplias species are similar in appearance and identifying them can be tricky. In fact, more often than not, fish hobbyists post pictures of their fishes to ask for positive identification of the species they have. Aside from the large size that H. aimara attains, it is in subtle differences visible only to the highly observant that one can identify a true H. aimara.
• Like most in the genus, H. aimara has an elongated cylindrical body shape. It develops a massive body as it grows older.
• The base body color may be light brown to dark grey with a number of generally thick vertical patches or stripes. However, this base color and pattern may vary from each type of locality of the H. aimara.
• The head of the H. aimara appears to be bigger and wider than most of the species.
• The eyes of the H. aimara appear bigger, especially when it is young, and these are not clear but rather, can best be described as “wall-eyed”.
• The teeth, like with all species in the genus, are impressive, jagged, and large.
The Key Distinct Features (KDFS) to look for that will help in positive identification of an H aimara are: • Small spots that are visible on the upper front portion of the body and on the head; and
• A vertically-elongated dark spot on opercular membrane or edge of the gill plate.