"Because they are 50 millimetres in size, they're a little bit too small to put a normal tag into. We've found an organic compound that we've effectively bathed them in at a small size and they've been able to take that up and it embeds on their bones," Mr Cooper explains.

The result is a new generation of fluorescent barramundi populating Lake Kununurra.

"It allows us to identify them, and of course there's absolutely no harm to anyone who wants to eat them," says Mr Cooper.