Shepshed, LEICESTER, UK. July 2nd, 2009. CyGEL Sustain (Biostatus Ltd., UK) now makes it simpler to image zebrafish (Danio rerio) embryos for microscopy, high content screening and for site-specific micro-injections, even from only a few hours post-fertilization. This thermo-reversible mountant is a liquid when cooled below room temperature and sets to a clear, optically-inert gel when warmed. CyGEL Sustain accepts embryo media and anaesthetics such as MS-222, when needed, to maintain yet completely immobilize de-chorionated embryos. After imaging, embryos can be easily recovered with excellent viability even after one hour in CyGEL Sustain thereby permitting observation of further development stages. CyGEL Sustain can equally be used for the mounting of fixed embryos. CyGEL Sustain avoids all the problems associated with methylcellulose and low-melting point agarose.