Behavioural elements of the paradise fish (Macropodus opercularis). I. Regularities of defensive behaviour.

Elements of behaviour were described for the paradise fish on the basis of the topography, location and orientation of the animal observed in various seminatural and laboratory environments. Correlations and repeatability of the parameters of observation were analyzed. Environmental influences, such as periods of the day, housing, feeding, raising conditions, presence of various frightening stimuli and species, and strain differences, were studied. Several functional connections were found among the behavioural elements.