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.

Tres nuevas especies de Hemibrycon (Characiformes: Characidae) de la cuenca del río Magdalena, Colombia. Fish biodiversity of aquatic ecosystems is highly threatened by different economic activities driven by human populations, and its description is increasingly a priority. For the Cauca-Magdalena River system we have described 14 species, and the purpose of this paper was to describe three new species belonging to the same genus Hemibrycon from the Nare and Guatapé River drainages of the middle Magdalena River, Colombia. The description was based on a series of 200 specimens, and the use of morphometric, meristic and osteological characters, as well as fish distribution and morphogeometric analytical methods. We have found that Hemibrycon fasciatus n. sp. (n=54) differs from other species of Hemibrycon (that also have a vertical humeral spot) in having: melanophores outlining the posterior margins of the scales along sides of body; humeral spot extending onto posterior margin of opercle; a dark lateral stripe, formed by deep pigment that is continuous with the peduncular spot; the toothed portion of the maxilla not reaching the dorsal margin of the dentary (vs. toothed portion of maxilla extending beyond dorsal margin of dentary); all maxillary teeth tricuspid (vs. some unicuspid teeth present on maxilla). H. cardalensis n. sp. (n=64) differs in having: a vertically elongate humeral spot that extends one or two scales below the lateral line canal. H. cardalensis n. sp. differs from all congeners in having the pigment of the caudal spot restricted to the ventral half of the caudal peduncle, and in having melanophores around the anterior scales of the lateral line. Hemibrycon antioquiae n. sp. (n=82) differs in having a circular humeral spot. It differs from the other species with a circular humeral spot, like H. mikrostiktos, in having a projection of disperse melanophores extending from the dorsal margin of the humeral spot to below the lateral stripe. Habitat data and environmental impacts caused by the construction of reservoirs for hydroelectric projects and other threats in the area are included, as well as a key to all species Hemibrycon present in the Magdalena River Basin. The synonymy of H. pautensis with H. polyodon is discussed and H. pautensis is revalidated. Rev. Biol. Trop. 61 (3): 1365-1387. Epub 2013 September 01.

Caracterización fisicoquímica y biológica del río Roble, Alto Cauca, occidente de Colombia. Para determinar las diferencias diarias y estaciónales, así como la productividad y el estado trófico del río Roble, un afluente de la Vieja, alto Cauca al occidente de Colombia, tomamos muestras de fitoplancton, zooplancton, peces y macroinvertebrados y registramos variables físico-químicas (oxígeno disuelto, porcentaje de saturación de oxígeno, pH, conductividad, humedad relativa, temperaturas ambiente, del agua, máximas y mínimas, ancho, profundidad, velocidad de la corriente, sustrato, CO 2 , DQO, DBO 5 , dureza total, dureza calcica y durezas magnesicas, sólidos totales, disueltos y suspendidos, alcalinidad , acidez, cloruros y turbidez) durante sequía y lluvias. La mayoría de las variables físico-químicas tales como la humedad relativa, oxígeno disuelto y porcentaje de saturación de oxígeno mostraron bajos coeficientes de variación, a excepción de déficit de oxígeno. El índice de diversidad de Shannon-Wiener, Equidad y Dominancia fueron bajos alrededor de 0.5. Registramos ocho órdenes, 28 familias y 58 géneros de macroinvertebrados, tres divisiones, cinco órdenes y 45 géneros de fitoplancton, dos divisiones y seis géneros de zooplancton y 19 especies de peces. El río Roble presentó un estado trófico heterotrófico-alóctono y es oligotrófico con tendencia a la eutroficación. Key words: Estado trófico, limnología, bioindicadores, quebrada, metabolismo.Resumen: To determine dial and seasonal differences as well as productivity and the trophic status of the lower Roble river, a tributary of the Vieja and upper Cauca rivers of west Colombia, we sampled phytoplankton, zooplankton, fish and macroinvertebrates and recorded physicochemical variables (dissolved oxygen, percent oxygen saturation, pH, conductivity, relative humidity, temperatures environmental, water, maximum and minimum, width, depth, current velocity, substrate, CO 2 , COD, BOD, total hardness, calcium and magnesium, total solids , dissolved and suspended, alkalinity, acidity, chlorine and turbidity) during the wet and dry seasons. Most physicochemical variables such as relative humidity, dissolved oxygen and percent oxygen saturation showed low coefficients of variation, except for oxygen deficit. The Shannon-Wiener diversity index, equity and dominance had low values around 0.5. We recorded eight orders, 28 families and 58 genera of macroinvertebrates, three divisions, five orders and 45 genera of phytoplankton, two divisions and six genera of zooplankton and 19 species of fishes. This river has an allochthonous-heterotrophic trophic state and productivity is oligotrophic but with a tendency to eutrophication.

Food and reproductive biology of Farlowella vittata (Siluriformes: Loricariidae) in Güejar River Basin, Orinoco, Colombia. Neotropical fish live in streams with considerable spatial and temporal variability of their food items. Food availability depends on different factors such as discharge, channel morphology, physicochemical conditions and interactions with other species, as well as their food habits. On the other side, good food availability results in reproductive success. Because the study of those changes contributes to a better understanding of trophic interactions in fish populations, the present work describes and evaluates aspects of diet and reproduction of Farlowella vittata in Pringamosal Creek, Güejar River drainage, Orinoco River basin, Colombia. Five collecting expeditions were done during both high and low rain seasons of 2008 and 2009. Physical and chemical water parameters were measured, and fish were captured from several points along the total length of the 7km stream, to characterize their biometry and stomach contents. Our results showed that Pringamosal creek is a first order stream, about 3.5m wide and with an average depth of 1m in our study area. Dissolved oxygen values were 6.2mg/L during low water and 2.7mg/L during high water phase. The creek is classified as oligotrophic but with a tendency to eutrophication. A total of 130 fish samples were analyzed. Fishes were assigned to seven size range categories between 86.0 and 175.5mm standard length (SL). Stomach contents revealed that the diet of this species consisted mainly of algae (Bacillariophyceae) (84.6% Abundance Relative), but we observed a variation in the diet according to season; during low rainfall it feeds on phytoplankton (86.47% A.R.) and during high rainfall on zooplankton as well as plant material and organic material (0.685% A.R. and 18.83% A.R., respectively). A Kruskal-Wallis ANOVA showed statistically significant differences in food items between sexes. The condition factor (K) indicated that the species was well fed. Size at sexual maturity was 154mm SL for males and 124mm SL for females. The gonadosomatic index (RGS) showed that this fish reproduced during high water (April-May) season, and females showed a fecundity of 1 819 ovocites, with an average diameter of 1.4mm. Although parental care was not observed during this study, it is well known that males protect their eggs and juveniles, making them easy to capture during the breeding periods identified in this study, and at the same time, vulnerable to overexploitation. We recommend an urgent management plan for the conservation of this species, since at this time, no fishing controls are enforced even though it is harvested as an ornamental species. Rev. Biol. Trop. 60 (4): 1873-1888. Epub 2012 December 01.