The Monaco’s Oceanographic Museum harbors one of the (and perhaps the) oldest captive reefs of the world. This reef is kept in a 40,000 liters semi-closed aquarium almost entirely balanced by implementing the Jaubert NNR system invented and perfected during 10 years (1979-1989) at the University of Nice (France). The tank was stocked in 1989 with live rocks, live sand, corals and fishes collected during a field trip in the Indian Ocean. The corals have built a reef, which is still thriving today after 25 years of uninterrupted development. At the time when coral reefs are under heavy pressure because of overexploitation, pollution and ocean acidification this successful experiment opens interesting prospects of ex situ conservation. The recent improvements of the carrying capacity of the ecological Jaubert NNR system might revive its popularity amongst hobbyists who need to keep many species of corals and fish but can’t invest too much time and efforts in the maintenance of closed-circuit tanks.