Dexy - Mate I may have jumped the gun in calling it a snoek, but as Tkei said, couta have stripes, and Snoek have spots...
I was actually judging it a snoek more by its proportions than its markings.... snoek are deeper bodied as well as having a slightly smaller head in comparison to their body than couta....
Can you remeber if it had spots or stripes?
Also, if that was a couta, its a pretty small to average couta.... but as a Snoek, its a trophy size, and far better eating too!!! So you should be even more stoked!!
Either way mate, congrats on your first mackeral species, may there be many more!