Zebrafish (danio rerio) and especially zebrafish larvae has become an important vertebrate model organism within the last 30 or so years. Now they became even more challenging with the invention of the CRISPR/Cas technology in the last few years. There are several reasons to use zebrafish as a vertebrate model: mainly the fast ex-utero development of the small nearly transparent larvae fish, which makes them very approachable for whole mount (fluorescence) in vivo microscopy, as well as the fact that they can be raised in large numbers on relatively small amount of space and therefore costs.
Thousands of mutant and transgenic zebrafish (reporter) lines have been established and described already worldwide and are easily available to everyone free of charge (Small handling fees for shipping of the fish-eggs might apply). Furthermore it is easy for everybody to transiently manipulate the larvae fish by injections of RNA, Morpholino® antisense knock-down constructs or overexpressing plasmid DNA which can also be used to raise stable transgenic fish-lines via germ line insertion within the next generation.
For further and more detailed information on zebrafish as model organism please also look at: