The wagtail platy is named for its fin pattern, which stacks on top of a body color. Red wag is the common version, with gold and blue wags also in the trade. It is a peaceful platy and a good first fish for a community tank.
Did you know
Wagtail, comet and tuxedo are three shop patterns that get confused, and where the black lands tells them apart. Wagtail blackens the whole caudal plus the dorsal and anal fins, while comet leaves black only on the tail's top and bottom edges. Tuxedo puts the black on the back half of the body instead.
Caring for the wagtail platy
Keep wagtail platies in a small group in a tank of at least 10 gal (38 L). Plants with some open swimming space suit them, and they spend most of their time in the middle of the tank.
Wagtail platies are hardy and forgiving, and they tolerate harder water well. Keep the water neutral to slightly alkaline, at 68 to 79°F (20 to 26°C) and a pH of 6.8 to 8.0. Feed a varied diet of flakes with some algae or vegetable content, and add frozen treats now and then.
They are peaceful and get along easily with other calm community fish. Keep more females than males, which eases the pressure on the females.
Females grow a bit larger than males. Wagtail platies bear live young rather than laying eggs, and they breed readily. A female can store sperm and drop several broods from one mating.
Good to know
On a wagtail platy, a name like Red Wag tells you both halves of the fish. Look for black that carries cleanly through the caudal, dorsal and anal fins, since weak lines show gray or patchy fins. The black sits in the fin rays, not across the flanks, so a red wag keeps a red body under jet fins. Melanophores packed along the rays produce it. Retailers often describe wagtail mouths as black too, but that detail is less consistent than the fins.
In the wild
The wagtail platy was fixed in domesticated platy stock and is not a wild pattern. Trade platies carry genes from more than one Xiphophorus species, and a breeder's own account ties the black fins to swordtail crossing. That account puts two X. maculatus genes behind the pattern, a bar gene and a twin bar gene. An enhancer from X. hellerii then spreads the black through the whole caudal and into the other fins. Who first fixed the line, and when, is not on record.
Weekly picks
Tank mates
The wagtail platy is a peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.
2.8 in (7 cm)15 gal (55 L)68–79°F (20–26°C)
2 in (5 cm)16 gal (60 L)68–79°F (20–26°C)
4.1 in (10.5 cm)29 gal (110 L)73–82°F (23–28°C)
2.8 in (7 cm)24 gal (90 L)68–81°F (20–27°C)
5.9 in (15 cm)20 gal (76 L)68–82°F (20–28°C)
3.5 in (9 cm)29 gal (110 L)68–79°F (20–26°C)