RésuméBoujard T., P. Luquet. In: The biology and culture of catfishes. M. Legendre, J.-P. Proteau eds. Aquat.Living Resour., 1996, Vol. 9, Hors série, 113-120.
Diel feeding rhythms and time of meals in Siluroidei.Siluroidei are said to have a mainly nocturnal trophic activity. This has been also observed under experimental conditions with fish that have constantly and free access to a food source. or with fish fed means of self-feedcrs. Nevertheless, it appears that the influence of IighUdark alternation on the trophic activity of some Siluriforms may be masked under restricted conditions of tempcrature or oxygen concentration. As a result, it can be pointed out that in the species studied, feeding activity takes place preferentially during the scotophase, but that this rhythm can be phase-shifted under specific environmental conditions. The hypothesis of an endogenous control of the feeding rhythms is discussed. In general, Siluriforms do not refuse to eat when fed during daytime. However, in view of the feeding rhythms of these species, it is worthwhile to evaluate the effect of such feeding time on the growth performance of the fish, and the metabolic utilization of the nutrients. Studies concerning the effect of meal time on growth performance show a better growth performance in Siluriforms fed by night. But this result should be taken with caution, because during most of the experiments undertaken, the fish showed very low growth performance, i.e. they did not expressed their maximum growth potential. Moreover, some authors provided evidence of a strongest effect of the feeding methvd (continuous feeding vs fractionned feeding into meals), than of the rime of feeding, on growth performance. In addition, real feed intake is never accurately rneasured. It is therefore impossible to determine whether the better growth performance observed in Siluriforms fed by night are caused by changes in voluntary feed intake or changes in nutrient retention efficiency. It is of further interest to stress that several authors showed a higher lipid content in Siluriforms fed by day (lowest growth performance) than in those fed by night (highest growth performance). It suggests an effect of feeding time on the use of the nutrients ingested.Keyworda: Feeding rhythms, circadian rhythms, feeding behaviour, meal time, growth, catfish.Les Siluroidei sont connus pour avoir, en milieu naturel, une activité trophique essentiellement nocturne. Ceci a été confirmé au cours d'expériences réalisées en conditions d'accès constant à une source de noumture, ou encore 2 l'aide de distributeurs d'aliments à la demande. Cependant, en conditions limitantes en température ou en oxygène, l'activité trophique de certains Siluroidei devient dépendante de ces deux facteurs, et n'est plus synchronisée par l'alternance jourlnuit. Le rythme nycthéméral d'activité trophique des espèces étudiées présenterait donc une acrophase préférentiellement nocturne, mais posséderait une certaine plasticité. L'existence d'un contrôle d'origine endogkne de c...