Southern Platyfish Identification Guide
Recognize the southern platyfish by its short rounded dorsal fin and dark 'moon' blotch near the tail base.
Read the full Southern Platyfish encyclopedia entry →
Key identification features
- Deep, compact, strongly laterally flattened body
- Rounded caudal and dorsal fins, with no sword or sail extension
- Wild coloration is olive to gray-green with a dark crescent or blotch ("moon" spot) near the base of the caudal fin
- Variable black speckling scattered over the flanks in wild populations
- Dorsal fin is short with relatively few rays (around 8-9)
- Males smaller (about 1.5 inches) with a gonopodium; females larger, up to 2.5 inches
- Body outline is noticeably rounder and more compact than most other livebearers
Common look-alikes
- Variable platyfish: has a taller dorsal fin with more rays (10-12) and greater natural color and pattern variability.
- Swordtail: males develop a long sword on the lower tail fin, which southern platyfish never grow.
- Molly: larger and more elongated, with an upturned, surface-feeding mouth.
Where you'll see one
Southern platyfish are native to quiet, weedy streams, drainage ditches, and spring-fed pools along the Atlantic slope of Mexico, primarily in Veracruz, extending south to Belize.
Frequently asked questions
How do I separate a southern platyfish from a variable platyfish?
Count the dorsal fin rays if possible: southern platyfish have a shorter dorsal with about 8-9 rays, while variable platyfish have a taller dorsal with 10-12 rays and show more varied coloration.
What single wild-type mark best confirms a southern platyfish?
Look for the dark crescent-shaped 'moon' blotch near the base of the tail fin on an otherwise olive-green body, a classic wild-type feature of this species.