Understanding behaviour to improve the welfare of an ornamental fish

Abstract

Some common practices in aquaculture, ornamental trade and fish facilities may disturb the behavioural repertoire of fish and its natural adaptive value, reducing welfare and impairing fish production. Hence, it is necessary to understand fish behaviour, as well as the factors affecting it, to improve the quality of fish's life under artificial environment. Here, we reviewed the behaviour of the angelfish Pterophyllum scalare, an Amazonian cichlid used worldwide both as an ornamental fish and as a fish model in scientific research. We characterized social, reproductive and feeding behaviour, as well as the amazing cognitive ability of the angelfish. In addition, we reviewed the effects of environmental enrichment and suggested some important variables that need to be considered for rearing P. scalare. In this review, we show for the first time a synthesis on behaviour and a best practice overview to improve the welfare of angelfish as a target species. Nonetheless, most topics reviewed fit a broader set of fish species, particularly ornamental ones. This synthesis can therefore open a path for further behavioural research applied to the welfare of angelfish and bring insights to other fish species.

Social behaviors as welfare indicators in teleost fish

“…Behavioral integrity can be used as a welfare indicator, since animals should be allowed to perform their natural repertoire of behavior to guarantee their overall welfare ( 140 ). To give an example, if reproduction succeeds it means that the artificial environment and housing conditions are adequate for fish welfare ( 141 ). As already explained in detail in section 3, cichlid fish have complex reproductive repertoire and, taking this behavioral variability into account, tank maintenance should provide optimal conditions for reproduction to occur, including an adequate sex-ratio, social hierarchy, breeding substrate and environmental enrichment that needs to be settled according to species-specific requirements.…”

How should we monitor welfare in the ornamental fish trade?

“…Territorial behaviour, such as being stationed near a shelter, refuge or feeding area, can be an indicator of indirect aggression in some ornamental fish species (e.g. angelfish, Pterophyllum scalare ), 143 but not all (e.g. the dwarf cichlid, Apistogramma agassizi ) 144 .…”

Video playback versus live stimuli to assess quantity discrimination in angelfish (Pterophyllum scalare)

“…The anatomical (e.g., large plate-like eye size, the optic lobes being the largest component of its brain mass, White Jr., 1975) and behavioral features of the angelfish (e.g., the previously mentioned visual discrimination abilities), also suggest that this species possesses good visual acuity. A detailed account for the social behavior, communication and cognition of angelfish has been published recently (Brandão et al, 2021), implying that angelfish will be an excellent model organism for experimental behavioral studies.…”