Parental care of Tilapia mariae in the field and in aquaria

Abstract

SynopsisParental care of Tilapia mariae was observed in nature (Ethiop River, Nigeria) and in aquaria with or without intruders present. In the field, 2530% of nests are guarded by one parent, normally the female. It is assumed that most missing males have deserted. Males who participate in brood care exhibit both close brood guarding and brood defence at a lower level than females, and hence seem to invest less than females. Broods were guarded under three distinct types: (1) female at the brood, male in surroundings, (2) parents take turns, or (3) parents stay together at the brood. Each pair used predominantly one type until the young swam freely, thereafter type 3. Females defended most in type 3, but male attack rate did not differ among the types. Type 3 seems related to increased risk of brood predation and type 2 to the female's foraging needs, being more common when she is small and the mates do not differ much in size. The unequal guarding times of type 1 indicate rather a low parental investment by the male (and thus risk of desertion) than specialization in roles on equal investment basis. Parental behaviour exhibited in aquaria differed in many ways from that in nature. The role types were indistinct and there were more signs of motivational conflict between the mates. Isolated pairs avoided joint guarding in the embryo period and while switching, female turns were much longer than male turns, unlike in nature. When intruders were added, males attacked them more than did females.

Reproductive strategies of two invasive tilapia species Oreochromis mossambicus and Tilapia mariae in northern Australia

“…Some studies, however, have reported plasticity in the reproductive behaviour of T. mariae , particularly in the manner in which parental care is exhibited (Bradford et al , 2011). Specifically, while T. mariae is primarily a monogamous species (Annett et al , 1999), there is evidence of bigamy and polygamy (Schwanck, 1989; Annett et al , 1999). In this current study, the average (both absolute and potential) fecundities of T. mariae at the two sites were not significantly different although in Nigeria, King & Etim (2004) noted considerable variation in the fecundity of T. mariae from various areas.…”

Effects of loss of male parent on brood survival in a biparental cichlid fish

“…Survival prospects for unguarded young are assumed to be very low unless they are nearing the age of independence from their parents (Keenleyside 1991). Mate desertion appears to be predominantly a male phenomenon (Kuwamura 1986, Keenleyside 1991, although three cases of apparently male-only care in the biparental species Tilapia mariae in the Ethiop River, Nigeria, were described by Schwanck (1989).…”

Reproductive behavior and parental roles of the cichlid fish Laetacara araguaiae

“…This inference could be supported by the higher investment in the nest building and rearing activities during pre-spawning and egg/wriggler phase, respectively. Moreover, the possession of a territory may have higher value for males, since they could to ensure attraction of other females and to have other spawning chances if they fail in a first attempt to reproduce (Schwanck, 1989). This is especially true to species whose males establish a territory before couple formation (Perrone, 1978;Neil, 1984).…”

“…Alternatively, the specialization in the execution of parental duties may be the result of differential ability to perform some particular tasks. For example, males usually are bigger than females and could be more effective in the territorial defense and, therefore, they would emphasize this activity (Barlow, 1974;Schwanck, 1989;Awata & Khoda, 2004;Itzkowitz et al, 2005).…”