It is blue kurper in their spawning colours. The top photo has the male (dark blue) and the female (lighter grey) in the picture. This time of the year they are protecting their nests while they wait for the eggs to hatch and after that the male nurses the small ones for another 3-4 weeks by protecting them and then if there is danger, taking them in his mouth.
If they do breed, you battle to get them to bite but with a small curley tail over or close to the nest you will get them to attack the lure. I do not promote catching kurper while they are breeding so give them another month and they will not leave a earthworm on a float alone and you will have a lot of fun catching them on light tackle. The problem with kurper is that birds and other fish prey on them and if you do not give them the best change to breed, you will not have a lot of kurper left in a dam after a few years.