Bullhead is a small, bottom-dwelling freshwater fish species. It used to be common in Flanders (Belgium) but nowadays only few and isolated populations remain. Consequently bullhead is listed as IUCN susceptible in the national Red List and fully protected. It is also listed in the EC Habitats Directive (92/43/EEC). Management should aim to conserve as large metapopulations in order to prevent further genetic loss. Until 2003, bullhead was thought to be extinct from the Demer River basin in Flanders. That year a relict population, genetically distinct from other populations, was found in a small tributary. This population is seriously endangered due to its small living area, population size and recent habitat deterioration. Since in situ protection proved to be difficult and insufficient, the Research Institute for Nature and Forest (INBO) and the Agency for Nature and Forest (ANB) initiated an ex situ conservation program. A suitable reintroduction location within the Demer River basin was carefully selected based on water and habitat quality and food availability. Meanwhile a captive breeding program was developed with brood stock extracted from the relict population. In October 2008 and 2009, cultured age 0+ bullhead were released. The success of this re-introduction was assessed each year by electric fishing. According to ecological and demographic criteria, the current conservation status is considered favorable. Recently, the Flemish government also adopted a population genetic approach, the so called Ne95 criterion, to assess the conservation status, which is presented here.