| Summary: | Groups of five small (12 - 18 cm) cod were kept in aquaria with two compartments, one with sand and one with stones and algae. When alone, the small fish usually spent most of the time in the compartment with stones and algae. When one large cod (25 - 38 cm) was introduced, different constellations occurred. When the big fish stayed in one compartment for some time, the small ones usually stayed in the other one. When the big fish frequently moved between the compartments, the small fish preferred to stay in the compartment with algae where they often were hiding. In one experiment the big fish stayed hidden among the algae, and the small fish apparently were not affected by its presence. Some small fish were eaten by the big fish during the experiments.
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