I keep 4 large specimens of Synodontis cf. petricola 'dwarf' - two of which are a pair, which bred before I got them - along with 4 Synodontis contractus in a 250L tank. The bottom of the tank is covered with a 15 mm layer of very fine sand and there are a number of rocks thrown in more or less randomly to make some hiding places for them.
When I fed my fish earlier tonight, I noticed a cloud of sand being 'blown' out between the rocks. Upon closer inspection, there was a rather large area between the rocks which was completely bare. The two largest petricolas seemed to be up to some thing in there, but it was really hard to see. Could this kind of behavior be associated with breeding ? In case it is, should I remove all but the adult pair of petricola to another tank ?