Electric signalling and reproductive behaviour in a mormyrid fish, the bulldog Marcusenius macrolepidotus (South African form

Abstract Bulldog fish (Marcusenius macrolepidotus) gener-ate short (<1 ms) electric-organ discharges (EODs), sepa-rated by much longer and highly variable interdischarge intervals (IDIs). We observed overt behaviour and electri-cal activity during reproductive behaviour in a male and in a female bulldog, and identified IDI patterns with putative signal functions. In contrast to Pollimyrus adspersus and Pollimyrus isidori, in which an elaborate and extended courtship precedes spawning proper, our fish started spawn-ing almost immediately when we allowed the female to enter the male’s territory. The male did not construct a nest, and neither parent provided parental care. The male showed very little aggression towards the intruding female. Fish spawned in bouts near the male’s hiding place, and eggs were scattered by the female’s vigorous tail flips as she lef