Broodstock spawning activity and filial cannibalism in orchid dottyback Pseudochromis fridmani (Klausewitz, 1968) under different rearing temperatures

Abstract

The orchid dottyback Pseudochromis fridmani is considered one of the most attractive species in the marine ornamental fish trade because of its bright colour, resilience, and relatively small size. Orchid dottyback aquaculture faces bottlenecks related to broodstock management and spawning conditioning, which make large-scale production challenging but can be addressed through targeted improvements. The present study addresses the knowledge gaps with regard to the management of P. fridmani under artificial conditions, describing the pair formation process with the associated behaviours, and the histological maturation process of gonads. The effects of low (25 °C) and high (28 °C) temperature on spawning activity and filial cannibalism were studied by monitoring six pairs for a period of 6 months. Water temperature strongly influenced broodstock spawning activity and filial cannibalism. The spawning rate increased significantly at 28 °C, but concurrent filial cannibalism also increased, leading to spawn losses. Notably, the total monthly number of viable spawns that successfully developed until hatching did not differ significantly between the 28 and 25 °C treatments. Examination of the size and shape of specimens sexed by histology (n = 6) suggested that these criteria may allow rapid visual sex identification in this species. Males tended to be longer and exhibited a more slender body shape, while females were comparatively shorter and showed a rounder body shape with a more pronounced belly. However, the accuracy of this method needs to be evaluated using larger sample sizes. In summary, maintaining the broodstock temperature around 25 °C facilitates the management of spawns and improves the performance of this highly demanded species.