yeah, there are no long term relationships with bristlenose. I chop and change my breeding pairs all the time to get the mix of fry that I want.
In terms of how to trigger them there are lots of ways. The more stubborn the fish, the more effort you need to put in. Just remember that if the male is not caved up then he is not going to be receptive to triggers. As Karl said, try to find some different caves and see how he likes them. once he has chosen one, take the others out and trigger away. there is a whole list of triggers in my book, from the common to the more rare tricks used by large scale breeders to get their stubborn fish to spawn.
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