An attempt is made to rank 41 steady-state models of aquatic ecosystems on the basis of their maturity. Maturity is quantified using several of Odum's attributes of ecosystem maturity. It is shown that it is possible to make such a ranking, and that the ranking seems to confirm our intuitive perception of ecosystem maturity. The ranking is compared to rankings based on various ecosystem goal functions. The maturity ranking shows a strong negative correlation with relative ascendency, and thus a strong positive correlation with system overhead, a possible measure of ecosystem stability. The analyses suggest that another goal function, exergy, as calculated here is mainly a function of system biomass, and that it might be appropriate to reconsider the computational aspect of exergy estimation. Most importantly the analyses point to the feasibility of using comparisons of ecosystem models as a tool for enhancing our understanding of ecosystem characteristics, notably sustainability.