Well-fed male catfish smell sexier to females, according to the results of a study published in a recent issue of the journal Behaviour.
Percilia Giaquinto of the State University of Sao Paulo tested the preference of female Pintado catfish (Pseudoplatystoma coruscans) for associating with well-fed or starved males in simultaneous choice tests.
The author carried out the experiments in tanks that were divided into three. Both a well-fed and a starved male were introduced into the end compartments, followed by a female into the central compartment an hour later.
Three different treatments were used in which females could choose on the basis of:
- both visual and chemical cues (transparent dividers were used and the water from the end compartments circulated into the central compartment);
- only chemical cues (opaque dividers were used and the water from the end compartments circulated into the central compartment);
- only visual cues were used (transparent dividers were used without circulation of the water).
It was found that the female catfish spent more time swimming near the compartment containing the well-fed male when both visual and chemical cues and only chemical cues were provided.
This implied that the female catfish was able to use odour to distinguish the nutritional status of the males. The author hypothesised that by preferring the scent of well-fed males, a female catfish chooses males that are not only in good nutritional condition but also have an effective immune defence.
For more information, see the paper: Giaquinto, PC (2010) Female pintado catfish choose well-fed males. Behaviour 147, pp. 319–332.