Turns out there is a very simple fix for this.
On the ASA
ssh key-exchange group dh-group14-sha1
Or as a quick work around you could add -oKexAlgorithms=+diffie-hellman-group1-sha1 in the client
bash>ssh -oKexAlgorithms=+diffie-hellman-group1-sha1 username@xxx.xxx.xxx.xxx