Background The Iberian Peninsula is one of the most important biodiversity hotspots of European freshwater fish species. Most of these native species are endemic to this geographic region, and the majority of them are threatened. The saramugo (Anaecypris hispanica), a fish species, is included in this group of endangered species. It is listed as ‘critically endangered’ in the ‘Portuguese Red Data Book of Vertebrates’ and is included in Annex II and IV of the EU Habitats Directive. The distribution range and population size of this species, however, has continued to decline over the past 40 years. This downward trend is increasing the risk of local extinctions and urgent action is needed to halt the species’ further decline. Objectives The project’s main aim is to strengthen saramugo populations by improving its habitat. Actions foreseen include: updating knowledge of populations in the Guadiana River basin enclosed in Portuguese territory; rehabilitating shelter, feeding and reproduction habitats and their connectivity; promoting habitat suitability for the saramugo, in order to allow future reintroductions or population reinforcements with specimens reproduced ex situ (preserving intraspecific diversity); clarifying the potential impacts of co-existence with the invasive bleak (Alburnus alburnus) testing barriers that could prevent bleak progression in areas of saramugo; reducing water pollution caused by livestock, in order to safeguard and improve water quality; and demonstrating techniques applicable to invasive alien species removal and expansion control, in order to reduce the impact of this threat. The project will also assess techniques’ suitability for replication in other sites and will contribute to the long-term conservation of saramugo through the participation of landowners, farmers, livestock producers, and decision makers. It will also raise public awareness. Expected results: Updated conservation status of the species’ population throughout the project area; A coherent and homogeneous database (using GIS) of information regarding the target species; Clarification of the impact of coexistence with the bleak; Identification of devices (cross barriers, electric current, specific pheromones etc.) that could be used as tools to control the progression of the bleak; Removal of invasive alien species in at least in three locations (two locations in Natura 2000 site Moura/Barrancos and one location in the Guadiana site), repeated over the three years in areas where they constitute a threat to saramugo populations; Protection of the waterways from negative impacts associated with livestock, including promoting the rehabilitation of riparian vegetation; Rehabilitation of saramugo’s habitat through sediment removal in two areas and 4 km riverside gallery recovery; Development and demonstration of an effective prototype barrier for halting the progression of the bleak; Implementation and testing one type of automatic device for the removal of invasive alien species; Workshop for sharing knowledge about exotic fish species control; Seminar to disseminate knowledge on the conservation of native fish and saramugo; Good practices manual for the conservation and rehabilitation of saramugo’s habitat; Raised awareness of the general public, landowners and stakeholders about their roles in the long-term conservation of this species and habitat.