Greater Seattle Aquarium Society

Yet Another Livebearer

by Dave Sanford
December 1998

When I noticed them in the dealers tank they were labeled as minnows. Considering the fact that the males had a rather large gonopodium they couldn’t be any species that I recognized as a minnow. As usual, I was intrigued by the identity of a fish I had never seen before. What species could they be? I narrowed it down to either genus Poecilia or Poeciliopsis on the basis of general body shape. The species determination would have to wait until I could look it up in Lothar Wiscanth’s Altas of Livebearers of the World. Four were purchased for id purposes as well as for the BAP points to be earned. Thumbing through the atlas, they were easily identified as Poeciliopsis gracilis, one of the many livebearers found in the streams flowing into both the Atlantic and Pacific in southern Mexico, Guatemala, and Honduras. The males get to 1 3/4 inches in length while the females can grow to 2-2 1/4 inches. The body coloration is greenish with a slight blue iridescence. Their flanks have 4 to 6 black irregular spots thus the common name porthole livebearer. Even the babies have the spots at about two weeks of age which makes it easy to distinguish them from other fry. All fins are clear or have just the slightest hint of color. The species name gracilis refers to the slender body shape, except for gravid females of course! I keep all of my livebearers at temperatures in the mid to high 70’s. Feedings consist of live baby and adult brine shrimp, earthworm and spirulina flakes. I usually mix two or more kinds of flakes together to insure variety. If kept well fed the adults don’t seem to take any interest in eating the fry, which are about 1/4 inch long at birth and have a preference for the surface. The females produce a brood at about 28 days after fertilization by the males. So far the maximum number of fry found has been eight. I suspect that more are born but get picked off by the other fish in the tank. When observed, the fry are caught and transferred to a five gallon rearing tank choked with Java moss. I haven’t determined if the females can store sperm for several broods like guppies do. Males constantly pursue females and each other. This hyperactivity probably limits their use as a dither fish for dwarf cichlids by they would be good for larger ones that can’t eat them. If you want a lot of action in a tank these hyperkinetic little fish will ad some zip to your tank.