Zoological Studies

Vol. 50 No. 4, 2011

Effects of Parental Care and Body Size on the Reproductive Success of the Paradise Fish Macropodus opercularis (L.) in a Small Area

Wen-Bin Huang1,2,* and Chih-Chieh Chang2

1Department of Natural Resources and Environmental Studies, National Dong Hwa University, 1 Da Hsueh Rd., Sec. 2 Shoufeng, Hualien 974, Taiwan
2Graduate Institute of Biological Resources and Technology, Meilun Campus, National Dong Hwa University, Hualien 974, Taiwan

Wen-Bin Huang and Chih-Chieh Chang (2011) The paradise fish Macropodus opercularis (L.) is a species famous for its predominant behaviors of male parental care, and in this territorial species, a larger male seems to have an advantage in terms of reproductive success. This study was conducted to examine the effect of parental care on the reproductive success of the paradise fish using different parental-care treatments of male-only care, female-only care, bi-parental care, and no-parental care. Hatching success of the paradise fish significantly differed among the 4 parental-care treatments. Hatching rates (HRs) averaged 94% for the male-only and bi-parental care treatments, 82% for female-only care, and 62% for no-parental care. There was no significant difference in HRs between maleonly and bi-parental care, suggesting that when the male is present, the female’s contribution toward hatching success is insignificant. Also, there were significant positive correlations of egg numbers (ENs) and HRs to standard lengths (SLs) of parental males (SLmale). Their regression relationships were: ln(EN) = 5.336 10-2 SLmale + 4.207 (r2 = 0.461) and HR = 2.511 SLmale - 53.806 (r2 = 0.661). These results suggest that reproductive success of the paradise fish primarily depends on male parental care. Based on the HRs, male fish were divided into 2 distinctive size groups: a small- (43.7-45.7 mm) and a large-size group (49.2-62.1 mm) with mean HRs of 48.6% and 90.0%, respectively. Accordingly, a minimum body length of about 49 mm was the size for the male to attain the plateau of a maximum HR.

Key words: Hatching rate, Egg number, Size effect, Breeding success, Labyrinth fish.

*Correspondence: Tel: 886-3-8227106 ext. 2261. Fax: 886-3-8230093. E-mail:bruce@mail.ndhu.edu.tw