Journal of the Marine Biological Association of India

Influence of lunar rhythm on spawning of clown anemonefish

Volume 49 Issue 1

Madhu, K. and Rema Madhu

Abstract

The influence of moon phases on the reproduction of the clown anemonefish Amphiprion percula from
Andaman and Nicobar islands was investigated during January 2002 to September 2005 for the first time in
India. Out of the 1281 fishes examined, the female to male ratio of 1: 2.1 observed for the entire period
indicated the predominance of males. The males were also smaller due to protandric sex conversion. The
influence of lunar phases and water temperature on the weight of gonad in different size groups of the species
was assessed. The gonado somatic indices (GSIs) showed a peak during January in females and males
whereas the lowest value in the former was observed in July and in the latter during June. The reproductive
pairs collected from the wild were reared in captivity and fed with gonad of green mussel, prawn and egg
mass of fishes six times daily @ 20% of the body weight in split doses. Apart from these, live feeds such as L
type rotifer, enriched with mixed micro algae isolated from Andaman waters, and Artemia nauplii and adults
were also provided. With these feeding schedule under aquarium conditions spawning in A. percula was
achieved on an average of 2.3 ± 0.3 month-1 throughout the year. Each fish laid 112 to 557 eggs between
0600 and 1545 hrs in 7 to 15 days interval with an annual number of 2500 to 13500 eggs. In all the pairs,
significantly higher percentage of spawning was observed 1-5 days after the full moon (I quarter) and new
moon (III quarter) than the IV quarter and II quarter which indicated that the spawning is related with lunar
periodicity. During the warmer period of the year, a maximum of 4 spawnings month-1pair -1 were obtained
indicating that water temperature ranging from 26.1 to 33.0ºC also had an influence on the frequency of
spawning under controlled conditions.

Keywords

Breeding, gonadosomatic index, spawning, lunar rhythm, Amphiprion percula

Date : 20-02-2008