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Which ostariophysan fishes use internal insemination?
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ostariophysan
Knifefish, or featherback (Xenomystus nigri)
While most ostariophysan fishes reproduce via external fertilization, there are specific exceptions to this rule. Internal insemination occurs in auchenipterid catfishes and South American characins belonging to the subfamily Glandulocaudinae.1
Despite this internal transfer of sperm, it is important to note that all ostariophysans are egg-layers; none of these species give birth to live young.1