This document introduces ECOLANG, a communica-tion language used for simulations of complex ecologi-cal systems. The language was developed with the main purpose of interchanging information between a simulation application of aquatic ecosystems (EcoDy-namo) and several external agents. These agents have some goals about the simulation results or the simulated system. Examples of the former may be a calibration agent, with the goal of optimising the fit between ob-served and simulated results, whereas an example of the latter may be an aquaculture/farming agent, looking for production optimisation. This document focus on messages exchanged between EcoDynamo and the two mentioned agents providing examples of the communication protocol. This work is part of a larger project, where ECOLANG will be used as a tool for "goal-oriented intelligent simulations", towards sustainable management of coastal ecosystems. This document introduces ECOLANG, a communica-tion language used for simulations of complex ecologi-cal systems. The language was developed with the main purpose of interchanging information between a simulation application of aquatic ecosystems (EcoDy-namo) and several external agents. These agents have some goals about the simulation results or the simulated system. Examples of the former may be a calibration agent, with the goal of optimising the fit between ob-served and simulated results, whereas an example of the latter may be an aquaculture/farming agent, looking for production optimisation. This document focus on messages exchanged between EcoDynamo and the two mentioned agents providing examples of the communication protocol. This work is part of a larger project, where ECOLANG will be used as a tool for "goal-oriented intelligent simulations", towards sustainable management of coastal ecosystems.