Aquatika, Public aquarium in Karlovac, Croatia.

Aquatika is a freshwater aquarium complex in Karlovac, designed by the Zagreb-based firm 3LHD and opened in 2016. Its 2,781-square-metre building presents Croatia's freshwater fish fauna and plant life, with 80 of the country's 150 freshwater fish species represented, 30 of them endemic. The exhibits trace the course of a karst river and its different habitats.

Aquatika was founded as part of the EU project "Kaquarium – freshwater aquarium and river museum", co-financed by the City of Karlovac and the European Regional Development Fund. Construction began in 2015 to designs by the Zagreb architectural firm 3LHD, and the complex was inaugurated on 22 October 2016 as Croatia's first freshwater aquarium of its size.

Aquatika's displays centre on Croatia's freshwater fish fauna: of the country's 150 freshwater fish species, 52 of them endemic, the aquarium keeps 80 species, 30 of which are endemic. Three permanent photo exhibitions, "Endemic Species of Croatian Rivers", "The Underground World" and "Croatian Rivers", present this biodiversity for teaching purposes. The institution also runs awareness work on freshwater ecosystems, with emphasis on local waters.

Aquatika stands at Ulica Branka Čavlovića Čavleka 1 A, on the Korana river beside the Branko Čavlović-Čavlek stadium. The 2,781 m² complex is laid out as a single route following a karst river from source to lower course, so visitors pass through the habitats in sequence rather than choosing among separate halls.

The tanks are arranged to follow a complete river journey from source to mouth, showing how species and habitats transform along the way. This layout lets visitors trace the natural progression of a river system in a single visit.