Spawning and Parental Behavior in Female Pairs of the Jewel Fish, Hemichromis Bimaculatus Gill

Abstract

AbstractSeven homosexual female pairs were observed on 17 occasions in a total of 22 spawnings. On six occasions the paired females spawned together. Four of the pairs synchronized so well in laying that they deposited rows of eggs alternately or simultaneously on the same site. In fifteen of the spawnings, the behavior of the "partner" of the first spawning female could be summarized as follows: seven ate the eggs and did not spawn until 3.5 days later; three ate eggs but spawned the same day ; three skimmed (or fanned) but did not spawn until 5 or more days later; and two skimmed (or fanned) and then spawned 10 and 45 minutes later, respectively. Hence the partners regarded the eggs as food (majority) or as offspring (minority). None of the partners could be regarded as showing male behavior since their skimming did not resemble the fertilizing movements of the male, except when both laid eggs. Pair formation depended on willingness of the females to inhibit their attacks on each other and to co-operate while maintaining a territory. Responses that seemed to check aggressiveness in the pair mate included the "estrous stance" and quivering. Homosexual groups that did not inhibit aggressiveness developed hierarchies and partial territories instead of pairs. On 11 of the 17 occasions of spawning, both females fanned the eggs and exhibited other parental behavior similar to that of heterosexual pairs. Twice, succcessful exchanges were made for fertilized spawn of Acquidens portalegrensis. These two pairs raised the young competently for 18 and 21 days, respectively, or fully as long as the heterosexual pairs maintained their young under our experimental conditions. It is concluded that female pairs of H. bimaculatus spawn in accordance with the chance synchronization of their separate estrous cycles, although some acceleration or inhibition of the cycle of the partner may result from the activities of the first to spawn. Since bisexual behavior could not be demonstrated, it appears likely that cichlid species performing the Hemichromis type of courtship have only one neuromuscular mechanism that with slight modifications is used by both sexes.