Fish embryos, like frog embryos, are generally much larger than human embryos (or corals embryos for that matter). Their larger size creates a challenge for cryo-freezing because traditional cryogenic techniques damages large embryos, rendering them nonviable. Up until this year, scientists did not know how to cyro-preserve frog embryos.
A team of scientists from the University of Newcastle has now discovered a method to slow-freeze larger embryos for the first time ever. The team hopes to expand this research to fish in order to conserve their genome. Scientists are already creating a gene bank for corals by freezing their gametes. Soon, they may be able to do same for fish as a "last line" insurance against extinction.