Measurements of reproductive effort from successive reproductive cycles for the Asian cichlid Etroplus maculatus

Abstract

Reproductive effort in fish through the time of spawning should include effort spent in producing gametes, territorial defense and courtship. This investment may be repeated if eggs are lost or the pair is separated after spawning has occurred. Little is known about how investments change when fish repeat reproduction. This study examined some changes in gamete production and courtship as initial pairs of orange chromides, Etroplus maculatus, were successively cycled with new partners after spawning had occurred. Results indicate that males’ fertilization rate remained the same throughout all cycles. Females’ egg number and total egg mass production also remained the same. However, the quality of individual eggs decreased significantly with every successive cycle. Changes in courtship behavior were also documented for some modal action patterns. It appears from these results that there are definite changes in both courtship and spawning characteristics from cycle to cycle. Therefore, the reproductive effort as a whole may change. In turn this may help select for the type of reproductive strategy observed in nature.