Alloparental Care In Clownfishes

In fishes parental care towards their eggs and young ones are well-known. Similarly fishes are rarely known to offer alloparental care (care given to non-descendant egg or young). Clownfishes are protandrous hermaphrodite (first male) and their social hierarchy allows formation of one female and a functional male in a group. This selection is typically based on the size and territorial domination/aggression of individuals. The hierarchy is altered only when a member is lost from the group i.e. when the female is lost the male changes sex (the testis in clownfish are generally ovotestis having both male and female component) and the next dominant individual becomes a functional male. This uptrend follows till the bottom of the hierarchy. In general the parental care in clownfishes is mainly the intermittent fanning of the eggs by males or rarely by females, mouthing of the eggs and removing the unfertilized and unhealthy eggs.

In order to find the alloparental behaviour in clownfishes sebae anemonefish Amphiprion sebae was used. The pairs used were selected from the broodstock nutrition research after completion of data recording. In that study different diets were used to find their influence on the egg and larval quality. The egg colour (to be precise the yolk pigmentation) typically reflected that of the dietary pigments. The initial egg colour remains only for two days and later turns dark with the embryo development (fig. 1). The deep sea prawn fed pair gave eggs with pinkish red colour which is typical to the crustacean pigment astaxanthin.

Fig. 1. Parental care in sebae clownfish

In this study two clutches (eggs) spawned on the same day was used. The clutches were distinctly pigmented with the diet used (see fig.2 and table 1). On the day of spawning the clutches were allowed to be with actual pair and on the second day noon the clutches were interchanged. Note the distinct colour difference between the eggs though the spawning substratum in both cases was same and the clutch position was also similar.

Fig. 2. Sebae clownfish eggs (clutch) on the PVC pipe

The PVC pipes were later interchanged and placed in different tanks in the same position. The fishes were observed for their behaviour. These fishes were used with such handling of clutch as it was frequently required for egg counting/photography and also sampling for embryo development. After few minutes the male came to inspect the clutch and returned immediately without fanning. There was no activity for a while, after half an hour he came again to repeat the same. After this initial hesitation everything went normal and the pair accepted the alien clutch and started caring them as usual. The pairs cared for the clutch for the five days and the adopted clutches hatched completely. The larvae were also found normal and healthy.

In this study the clutch colour and intensity were distinctly different, thus itŐs highly unlikely to assume that the pairs were unaware of the clutch change. Another important factor is that these egg pigmentations (diets) were followed for at least six successive spawning as that data were necessary for the research work. More studies on alloparental care in clownfishes may give insights into their behaviour and hierarchy.

Suggested reading:

Alloparental care in fishes by Brian D. Wisenden (Review article in the journal Reviews in Fish Biology and Fisheries 9: 45 - 70, 1999)