The importance of animal components in the diet of adult rabbitfish Siganus fuscescens

Rena Shibata, Satoshi Katayama, Satoshi Watanabe, Hisayuki Arakawa

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2 Citations (Scopus)


The importance of animal matter in the diet of the adult rabbitfish Siganus fuscescens was determined using a combination of composition analysis of the diet and rearing experiments. The gut contents of rabbitfish inhabiting a barren area or a seaweed bed consisted mainly of macroalgae with a smaller concentration of animal matter such as hydrozoas and crustaceans. The carbon/nitrogen stable isotope ratios (δ 13C and δ 15N) of rabbitfish living in the barren area were significantly lower than those of rabbitfish inhabiting the seaweed bed. This difference in the ratios is probably due to the lower concentrations of δ 13C and δ 15N found in crustaceans which are the main food source for rabbitfish inhabiting the barren area as compared to the concentrations of δ 13C and δ 15N provided by algae and other animals as a food source. Rabbitfish reared on brown algae alone showed reduced somatic growth, whereas the fish fed with krill and gammarid exhibited a greater increase in body weight and were found to be in better overall condition. Concentrations of δ 13C and δ 15N in the fish fed only with brown algae showed a small shift during the rearing period. Thus, although the rabbitfish is regarded to be omnivorous with strong herbivorous tendencies, it appears that the inclusion of animal matter in their diet is also important for satisfactory growth.

Original languageEnglish
Pages (from-to)103-111
Number of pages9
JournalLa Mer
Issue number3-4
Publication statusPublished - 2010 Dec


  • Diet composition
  • Feeding habit
  • Siganus fuscecens
  • Stable isotope ratio


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