núm. 6-7 (2007)

Comercial fish production in Rionegro, Santander, Colombia is a important issue to regional economy, however, these are not subjet studies about association of pathologies with mortalities showed in fish which would be important to impone productivity. The insure of the study was to confirm by histopathology the presence of parasites on Mojarra Roja (Oreochromis spp.) and Cachama (Piaractus brachypomus). 50 mative fish from a commercial piscicola were taken and samples (heart, gills, muscle, skin, gonads, kidney, bile vesicle, liver, brain, stomach and eyes) from then were processed by histopathologic with hematoxilin-eosine, to determine parasitic infestation. Parasitic infestation was correlated with ph, turbidity and temperature of water. The datas were analized by descriptive statistics. Macroscopic lesions founded in Mojarra Red (Oreochromis spp.) were yellowing pale liver, gall bladder, intestines pletórica congested and congested gills and in Cachama (Piaracuts brachypomus) were congested gills, yellowing pale liver, stomach and intestines congested. Data from Oreochromis spp. showed that as temperature and turbity low, parasitism and parasitism related lesions on gills raises while Piaractus brachypomus seens to be resistant to temperature and turbity changes. In both cases (Oreochromis and Piaractus brachypomus) other that gills-related lesions seems to be associated with nutricional on bacterial causes.