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Teleost fish show tremendous variation in breeding systems. In particular, indeterminate growth and external fertilization create great disparities in reproductive success among males, which drive the evolution of male reproductive polymorphisms. Here, we present evidence for alternative male reproductive tactics in Neolamprologus modestus, a substrate‐spawning African cichlid fish. We observed two types of males in our study site: (1) males that guarded large territories comprised of smaller subterritories of several females and (2) males that did not hold territories and were vigorously attacked by the guarding males upon intrusion into the guarding male's territory. We hypothesized that these intruder males constitute an alternative male phenotype. To test this hypothesis, we collected both territorial males and these intruder males to determine if there were differences in overall body size, gonad size, age or …