1. In some species, the gonopodium may be half the total body length. 2. When ready for mating, the gonopodium becomes erect and points forward towards the female. 3. "O . dovii " has no gonopodium like the other members of its family. 4. The male uses his modified anal fin, or gonopodium , to deliver sperm to the female. 5. Fertilization is internal; the male secretes milt into the genital aperture of the female through his gonopodium . 6. If a female remains stationary and her partner contacts her vent with his gonopodium , she is fertilized. 7. In guppies, the male s gonopodium can cause damage when forcefully inserted, causing cloacal damage to the females. 8. The anal fin of the male fish has evolved into a gonopodium , a stick-shaped organ used for reproduction. 9. Like most poeciliids, males'anal fins are modified into a gonopodium that is used for impregnating females during mating. 10. The gonopodium of " Neoheterandria elegans " males has a long, bony rod that projects forward and downward.