COURTSHIP BEHAVIOUR OF BRAZILIAN BASSLET Gramma brasiliensis (SAZIMA, GASPARINI & MOURA, 1998) IN CAPTIVITY

The Laboratory of Marine Fish and Ornamentals has been working with Gramma brasiliensis for several years and only a few spawning events have been observed. Trying to improve their spawning frequency, we tried to understand more about the reproductive and behavioural aspects of this species, and therefore the following question still need to be answered: "What behaviour indicates that couples may be actively reproducing and spawning in captivity?" This work compares the reproductive behaviour described for the Caribbean species Gramma loreto in the wild with the behaviour verified in aquariums with couples of G. brasiliensis.

Two pairs of G. brasiliensis, each one kept in 110-L aquariums, were monitored. A total of 39 h of video recordings were made (Nov 2018 - Aug 2019), always in the morning (9 to 11 a.m.).

Courtship behaviour of the couples followed some patterns. The males` courtship behaviour was always the same, an U-turn with body quivering, similar to one described for G. loreto; courtship event that led females enter the males` nest for spawning. We can summarize it as follows: The male approaches, standing in front of or beside the female, turns his body quivering (except when he is already heading towards the nest) and immediately goes towards the nest by swimming quickly and with his body quivering. Periodically, usually when females showed some interest (i.e. following the male towards the nest), the male repeated        U-turns to attract the female into the nest. Description of the behaviour performed by males and females are summarized in Table 1 and Figure 1.

Repetitions of the U-turns sequences  (mean 4.0, mode 2; n=149) varied from 2 to 21 movement displays. From 149 times, the females followed the males all the way and entered the nest in 19.5% of them.

The mean time the couple remained inside the nest was 65.6 ± 47.6 seconds. In all cases, the male entered the nest first and in 79.3% of the times the female exited the nest first.

We found some similar behaviour of this species in captivity when compared         G. loreto in the wild, such as U-turn BQ and some female responses. However, during this experiment, there was only one spawning event verified. The reasons for this lack of spawning, even though the occurrence of courtship, remains to be elucidated.

Acknowledgments: CNPq (National Council for Scientific and Technological Development) and CAPES (Coordination for the Improvement of Higher Education Personnel) for their support funding the research.