Abstract The evolution of the C.E.B.A.S-AQUARACK project including results of the scientific frame program was frequently presented at the IAA Man in Space Symposia 1989 and 1991 and the IAF/IAA congresses since 1990. C.E.B.A.S. (Closed Equilibrated Biological Aquatic System) is a combined animal/plant system for long-term multi-generation experiments with aquatic organisms in ground laboratories and in a space station. For short-term missions a miniaturized version was developed which fits into a spacelab middeck locker together with all surrounding equipment. The latest development is an optimized prototype with a total volume of about 11 liters which consists of a main animal tank (Zoological Component) with integrated bacteria filter, a semibiological coarse filter, an illuminated higher plant container (Botanical Component) and combined small animal and electrode compartment. A silastic tubing gas exchanger in a closed side-loop serves as an emergency unit in case of the malfunction of the Botanical Component and the water is driven through the system by rotatory pumps. It is operative for several weeks in closed state. This C.E.B.A.S. Mini-Module also represents an aquatic artificial ecosystem in which basic scientific problems of component interactions and system theory can be solved with the side aspects of combined production of animal and plant food in bioregenerative life support systems. The paper presents details of the current statuts of the hardware development and data about the function of the fully biological life support of the system, e. g. mid-term registrations of water parameters. Moreover, morphological and pysiological data of the experimental animals (-the teleost fish Xiphophorus helleri-) and plants (-a tropical Ceratophyllum species-) demonstrate the biological stability of the system. These are used to elaborate first details of population interactions and inter-dependencies as a basis of a disposed comprehensive system analysis which is the essential precondition for the design of possible aquatic modules for bioregenerative life support systems.