In my last post I discussed the artificial colouring of ornamental fish species by dye injection. That there are other ways to influence the colour of ornamental fish is shown in a recent paper published in the Animal Behaviour journal.

A group of scientists studied the effect of dietary pigments on skin pigmentation, growth and behaviour of male flame-red dwarf gourami, Colisa lalia. The fish were fed either a control diet or one of three different diets, Lucantin Pink, beetroot juice powder or Overseal Carantho powder, daily for 12 weeks. The addition of synthetic astaxanthin (Lucantin Pink) significantly increased red coloration, whereas betalain-based (beetroot juice powder) and anthocyanin-based (Overseal Carantho powder) pigments did not affect skin colour. Fish fed the test diets showed a similar growth than fish fed the control diet.
The increased red coloration also affected the popularity of the C. lalia males. Females C. lalia interacted more and spent more time with males fed the diet containing Lucantin Pink than fish fed the control diet. Such effects were not seen in fish fed the other two test diets.

For more information, see the paper: Baron, M., Davies, S., Alexander, L., Snellgrove, D., Sloman, K.A., 2008. The effect of dietary pigments on the coloration and behaviour of flame-red dwarf gourami, Colisa lalia. Animal Behaviour, 75, 1041-1051.