I'm gonna have to agree with everyone else. I'm afraid that wasn't the best idea. The fish had already survived for a few days, right? You could have started doing daily 50% water changes. That would have brought the nitrites and ammonia done in the quarantine tank.It was kinda late at night and the QT tank had very very high nitrite... Either way he could die but he has a better chance in the main tank. He would have died no doubt in the QT tank. Cause I'm adding ammonia and stuff to it soooo.... In order to put him in the breeder box i would have had to take the light and lid off of the main tank and then move the breeder box from the QT tank to the main tank which would be a pain while its a mesh one that pours out water while you move it... Also, mmaybe its an enrichment thing for the fish. You know, hunting? I bet the female got some fun adrenaline going while chasing it . But I promise you if I see it I will TRY to move it to the breeder box. At the moment I was just trying to get it out of immediate danger. I didnt have time to move everything. All my dragon rock is in the QT tank so by the time I came back to him he could have hidden and then I would've been like: "Well, too bad little buddy. I'm adding ammonia in a few days so ya better show up." I feel like I made the best decision with the time I HAD. It was kinda like saving a person with a terminal disease in an area that had poison gas. You could just go: "Well he's gonna die anyways" or you can do the right thing and rescue them even though they may have a week left to live.
And just because it would have been too much work to move the breeder box over you decided to take the easy way and put a baby fish in with something that 100% wants it as dinner?
And then to take the life of the fish so lightly and say "maybe the female got some fun adrenaline going while chasing it"?
You could have netted it into the breeder box in the quarentine tank so you could keep and eye on it then taken the cover and light of the main tank and moved the breeder box over. Made a mess? Just wipe it up!
Just my thoughts