Simple techniques for labelling prey and gut content analysis in short-term feeding experiments with fish larvae

Techniques were developed for labelling prey, and for gut content analysis in fish larvae. Labelling consisted of a short feeding period of the prey ( rotifer and Artemia metanauplii) on black-drawing ink before supplying them to the larvae. Prey labelling was rapid and remained stable for at least 3 h when transferred into seawater. In addition, a method was tested to faci litate the observation of larval gut contents. The method, based on Dawson' s technique, involved fixation, removal of lipids and clearance of turbot ( Psetta maxima) larvae, which become transparent and ready for gut content a nalysis. This treatment did not interfere with the black ink label of the i ngested prey. (C) Ifremer/Cnrs/Inra/Ird/Cemagref/Elsevier, Paris.