Titicaca orestias

Each species of Orestias has varying size. The Titicaca orestias was the largest species in the genus.[4] The maximum recorded size is 22 cm (8.7 in) in standard length and 27 cm (10.6 in) in total length, which is considerably larger than most other species; only O. pentlandii at up to 20 cm (7.9 in) and 23.5 cm (9.3 in), respectively, comes close.[3][5][6]

With regard to the coloration of the amanto during their lifetime, specimens present black melanophores laterally as a band on the lateral line and as small groups on the upper lateral sides. Small melanophores cover the fins giving them a grayish color. The grayish color fades to white on the dorsum and belly; juvenile pigmentation pattern persists with little modification in adult males and females.[4] This information shows that the color of the Orestias in question depends on what part of the body is being considered.

Nothing has been published about the reproduction of the Titicaca orestias, but in other Orestias species of Lake Titicaca, the males become more orange or yellow in color when they are spawning. During their reproductive stage, the females lay somewhere between 50 and 400 eggs, each of which has a yellowish filament up to about 2.5 mm in diameter. As an adaptation to solar radiation, the eggs develop a black protective coat, derived from melanophores, around the embryo sac.[4]

The freshwater fish belonging to the genus Orestias are found in high-altitude isolated lakes in the Altiplano region of South America, ranging from Peru to Chile. Lake Titicaca, which is on the border of Peru and Bolivia, contains a wide variety of Orestias fish.[7] This large lake was once the home to Orestias cuvieri before their extinction.

At one time, there were as many as 30 native fish species in Lake Titicaca, of which 28 species belonged to the genus Orestias. In the middle of the 20th century, there were many attempts to introduce exotic species to the lake. Two of these introductions were successful: rainbow trout introduced in 1942 and silverside (Odontesthes bonariensis) in the early 1950s. The success of the silverside meant the decline of the Titicaca orestias, since the larger silversides were observed to eat them. As long as the silverside continued to flourish, it meant difficult times for the amanto. Fifty years ago, there was no sign of Orestias cuvieri in Lake Titicaca and the species was presumed to be extinct.

O. cuvieri mainly ate smaller fish.[4]

With regard to law enforcement, major efforts are still needed to prevent pollution and illegal fishing. These efforts need to be made specifically on the area, between Peru and Bolivia, of Lake Titicaca. O cuvieri has likely already become extinct. Other native species, including the suche (Trichomycterus rivulatus), boga (O. pentlandii), yellow karachi (O. albus) and ispi (O. ispi), are threatened to various degrees, as a result of overfishing, predation by introduced species, and the impacts of intensive production in trout farms.[9] This idea of law enforcement is particularly challenging because of the immense body of water that would need patrolling. Actions to be on the lookout for by law enforcement should include long casting; where a long line (over 100 kilometers in some instances) is cast and other unintended fish are caught. Perhaps more importantly though is to be on the lookout, as an entity of law enforcement for pollution.