The nest itself isn't the behavioral building problem, it's "mating season"
being fed well, warm water, clean water... all contribute. That doesn't mean you should starve him, stop cleaning and keep the heater off!! :o But if he does en up hurting himself or another fish it would be best to remove him. I never had that problem with Spartan, as he was older when he was with other fish - and when he was 6 months I had him with fish at first and he did chase when he was younger....eventually he gave up
Breed for the breed, not for the money; the words any REAL breeder would understand.
You must know nothing in order to know all, for all is nothing and nothing is for all.