An Experimental Study of the Building Behaviour Sequence of a Shell-Breeding Cichlid-Fish From Lake Tanganyika (Lamprologus Ocellatus)

The cichlid-fish Lamprologus ocellatus (POLL, 1986) digs empty snail shells into sandy substratum, using them for dwelling and breeding. The sequence of building behaviour was analysed. It can be divided into three phases: (1) in the inspection phase the fish swims into and around the snail shell; (2) while during the digging phase sand is moved away from the shell; (3) in the subsequent oversanding phase, the shell is covered with sand. In the analysis of the building behaviour sequences of eight individuals, each of which performed five trials, interindividual differnces were found, but there were no differences among repeated trials of one individual. In the comparison of building procedures on small- and medium-sized shells we noted a dependence of the number of building actions and of the building duration on the size of the snail shell. By offering an artificial sandpit, the digging-phase may be shortened or not take place at all. By enlarging the interior of the pit the oversanding-phase can be lengthened. This led to the conclusion that the behaviour sequence, especially onset and end of the individual phases, is induced and controlled by the change in the external stimulus situation, which is influenced by the performance of the building actions. Information on the progress of building is perceived through the shell-contact-act (cont) in which the fish swims to the snail shell. It alternates with the building activities. The results of the "experiments in an artificial steep-walled pit" (2,2) indicate a visually controlled orientation.

Affiliations: 1: (. Zoologisches Institut und Museum, Universität Göttingen, B.R.D.