The remarkable fish diversity in the Caribbean rivers of north-western South America evolved under the influences of the dramatic environmental changes of neogene northern South America, including the Quechua Orogeny and Pleistocene climate oscillations. Although this region is not the richest in South America, endemism is very high. Fish assemblage structure is unique to each of the four aquatic systems identified (rivers, streams, floodplain lakes and reservoirs) and community dynamics are highly synchronized with the mono-modal or bi-modal flooding pulse of the rainy seasons. The highly seasonal multispecies fishery is based on migratory species. Freshwater fish conservation is a challenge for Colombian environmental institutions because the Caribbean trans-Andean basins are the focus of the economic development of Colombian society, so management measures must be directed to protect aquatic habitat and their connectivity. These two management strategies are the only way for helping fish species conservation and sustainable fisheries.

A new species of Hyphessobrycon (Characiformes: Characidae) from the Telembí River drainage, Southern Pacific slope of Colombia. The genus Hyphessobrycon is included within the subfamily Tetragonopterinae. The species are generally small, do not exceed 70mm of standard length, are economically important as ornamental fish, with 128 valid species distributed from Southern Mexico to Rio La Plata in Argentina. The collections of fish were made with seines, in a single biotope, along shore in backwaters and working downstream. Measurements of the specimens were taken point to point with digital calipers. Observations of bone and cartilage structures were made on cleared and stained (C&S) specimens. The morphometric relationships between species were explored using a principal component analysis (PCA)using 21 variables. We described a new species, Hyphessobrycon chocoensis, from the Telembí River drainage of the Pacific versant of Colombia. The new species, Hyphessobrycon chocoensis, is distinguished from congeners not of the "flammeus" species group by: having a diffuse humeral spot, in lacking a dark spot on the dorsal fin and caudal peduncle. It is distinguished from members its species group by the number of rays in the dorsal fin (ii, 8, i), by the number of branched anal-fin rays (25-26) and by having a diffuse humeral spot. It differs from H. tortuguerae in the number of teeth on the maxilla (1-2), by the number of predorsal scales and the high number of scales between the lateral line and the anal fin (6-7). Hyphessobrycon chocoensis can be distinguished from the other known species of Hyphessobrycon from the Pacific Coast of Colombia in having: a high number of pored lateral-line scales, by the snout to dorsal-fin length, by caudal-peduncle depth and by eye diameter. In addition, it differs from H. columbianus by the distance from the dorsal fin to the anal fin, by the length of the upper jaw, and by snout length. It differs from H. condotensis in having a high number of scales between the lateral line and the dorsal fin, and by the number of simple rays in the anal fin. H. chocoensis is distinguished from H. sebastiani by the number of transverse scales and the number of scales between the lateral line and the dorsal fin. A taxonomic key is provided to aid with the identification of the species of Hyphessobrycon from the

Este libro nos pone al día en tres grandes bloques, uno inicial donde se aborda el estado del conocimiento tanto desde la perspectiva biótica como física de la cuenca, la geología, hidrología, sedimentología y su relación con los ecosistemas y la biodiversidad acuática; los peces, su diversidad taxonómica y genética, ecología e historias de vida y los servicios ecosistémicos que brindan como recursos pesqueros. En la segunda parte se consideran los conflictos ambientales en la cuenca, desde temas como la contaminación y la modificación del hábitat; los peces introducidos (exóticos y trasplantados y la “presión” de una demanda cada vez mayor de la pesca. En la sección tercera, tras una interpretación concienzuda de los capítulos anteriores y el conocimiento de los investigadores, se hace un análisis detallado de todas las amenazas, así como las estrategias de conservación y manejo del recurso íctico. Todo ello, sienta las bases para una serie de recomendaciones para la toma de decisiones que son recogidas al final de la obra.

Hyphessobrycon oritoensis (Characiformes: Characidae) is described from the Putumayo River drainage of the Colombian Amazon. The new species belongs to the H. heterorhabdus group and is distinguished from all other known species by the following combination of characters: iii,8 dorsal–fin rays, iv, 26–27 anal–fin rays, 19 teeth on dentary, 35 scales in longitudinal series, 10–11 perforated scales in lateral line, 7 scales between lateral line and dorsal–fin origin, 14 predorsal scales and a dark lateral band that extends from the posterior border of the humeral spot to the tips of the middle caudal fin rays.

We describe a new species, Hyphessobrycon sebastiani, from the San Juan River drainage of the Pacific versant of Colombia. This new species of Hyphessobrycon is distinguished from all congeners that share two humeral spots and no caudal blotch by having: five unbranched and 25 to 28 branched anal–fin rays; 12–13 branched pectoral–fin rays; 35–37 scales in the longitudinal series; eight scales between the lateral line and the dorsal–fin origin; 12–13 predorsal scales; 13–18 pored lateral–line scales and three pairs of large bony hooks on anal fin of mature males.