Goodea gracilis Adult Female. Photo by Rick Borstein

Common Name: Dusky Splitfin, Slender Splitfin
Synonyms: None


Genus- Goodea= I believe it to mean bonus (Latin).
Species- atripinnis= black finned atri=black, pinnis= fin (Latin).
Subspeciesgracilis= slender (Latin).


The Dusky Livebearer is a vulnerable species of Goodeid from Mexico that is threatened by the introduction of invasive species. Like other goodeids, it sometimes has an attitude and will chase more peaceful fish.

Both males and females have an overall "dusky" grey-green tone, hence the common name. This fish is often sold as either Goodea gracilus or Goodea attripinus. It is unclear to me what the correct scientific name is at the moment.


Like all Goodeid, the Black-Finned  Goodeid is from Mexico. They are found throughout the Rio Punoco drainage.

Size, Maturity, and Sexual Dimorphism

Size: Males- 3 inches, Females- 6 inches
Maturity: 2 inches
Sexual Dimorphism: Males are smaller than females and possess darker fins. Males also have a modified anal fin for reproduction called an andropodium. This can be seen as a notch in the anal fin.


Dusk Fin Livebearers are easy to keep. Like most goodeids, they prefer cooler water that is 75F or less. I think they do best at 70-72F. 


These fish are omnivorous and will eat anything in captivity. They especially like live baby brine shrimp.


Goodea gracilis breeds like other goodeids. The male gets close to the female and transfers sperm packets to her via his andropodium. This species has a very long gestation period, almost two months. The fry are huge when born, and number between 5 and 30. The fry hang at the top of the tank for their first week out of the womb. Fry are easy to raise on either baby brine shrimp, or crushed flake, and grow quickly. 


Although not a colorful fish, Goodea gracilis is critically endangered, and needs our help. It may be difficult to find, but if you see them available, pick them up.


  • IUCN. IUCN Red List of Threatened Species. <>.
  • Miller, R.R., Minckley, W.L. & Norris, S.M. (2005) Freshwater Fishes of México. Museum of Zoology, University of Michigan, & University of Chicago Press, Chicago, 652 pp.

Goodea gracilus Male