Fast, easy and early (larval) identification of transparent mutant zebrafish using standard fluorescence microscopy

The availability of transparent zebrafish mutants (either TraNac: tra (b6/b6); nac (w2/w2 )or casper: roy (a9/a9); nac (w2/w2)) for live imaging studies together with the ease of generating transgenic lines are two of the strengths of the zebrafish model organism. The fact that transparent casper ( roy (a9/a9);nac (w2/w2)) and silver nacre ( nac (w2/w2)) mutants are indistinguishable by eye at early stages (1-5 days post-fertilization; dpf) means many fish must be raised and later culled if they are not transparent. To identify translucent mutants early and easily at the early larval stage (≤5 dpf) before they are classified as protected animals, we developed a simple screening method using standard fluorescence microscopy. We estimate that this procedure could annually save 60,000 animals worldwide.