Marigold swordtails are a type of freshwater aquarium fish that originate from Central America. They are a popular small fish for tanks, and like all Xiphophorus helleri, or swordtails, they are recognizable by the swordlike shape of the tail fin. Before integrating this type of fish into a current or new tank, it is necessary to learn the basic facts about them to further enhance your enjoyment.
The marigold swordtail gets its name from the swordlike extension from the tail or caudal fin of the male fish. This is a characteristic that is seen only in the males, which also have a tubular or sword-shaped anal fin called the gonopodium. The female caudal and anal fins are fan shaped. The marigold swordtails are orange or gold that darkens to red toward the tail fin. The swordlike protrusion of the male's caudal fin is fully or partially black. The male marigold swordtail, at 3 inches, is generally smaller and thinner than the female, who has a more rounded appearance.
Marigold swordtails are live-bearing fish that can give birth to up to 100 fry every 28 days. Breeding will typically occur as long as there is a male and female in the same tank. When pregnant, the female develops a dark spot at her anal fin called the gravid spot. The fish cannibalize their young if they are left in the same tank.
Typically, the marigold swordtail is a peaceful fish that gets along with other community fish that are similar or slightly larger in size. Male fish can become more hostile and aggressive toward other males as they mature. If kept in a tank with one female only, the male will harass the female, which can result in injury or death.
Certain water conditions are necessary for healthy marigold swordtails. They require water temperature between 64 and 82 degrees Fahrenheit. In addition, the pH level should be between 7.0 and 8.3 and they have a preference for hard water. Because they are an active fish, they require a tank that is 10 gallons or larger.
Like all swordtails, the marigold swordtail is omnivorous and eats a wide variety of food, including tropical flakes and plants. Dried or frozen bloodworms, insects and brine shrimp are also types of food that the swordtail consumes.