Flag acaras will pair up at a very young age, as small as one and a half inches. The fish will flare at each other when pairing up and will later swim together and breed. They usually stay with their mate for the rest of their lives. It does not take much to trigger the breeding of these fish. Simple good treatment is more than often enough, although warm and clean water and much live food will help. They will almost always lay their eggs on a flat surface, but may spawn directly on gravel.