How long after birth does a swordtail fish grow its sword tail?
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Expert Answer
A male swordtail’s sword (lower caudal fin extension) starts developing 3 months after birth. Male and female tails differ; only males have the sword, females have round tails. Male youngsters also have round tails that grow the sword with development. Swordtails mature at 6 to 8 months; pick beautiful, high-finned, brightly colored, well-developed adults as breeding stock for fine offspring.