Are they old enough yes, they can breed soon as they produce sperm plug.

Now will they breed? Not always.

Over the past six season I had no luck with males under 600 grams, you can try but it may not work.

You also need to closely monitor the males a smaller males and not breed them too often (which they don't need anyway) and if a male stop eating and start losing weight (and they will as breeding take a toll on them) you will need to remove the male from rotation.

Males that are smaller but eat throughout the season are less of a worry.

The good news is since you do not have a female and once you have her you need to add at least 3 months of quarantine before being able to pair them, this will give you time to bulk them up some more.