About Xiphophorus hellerii Heckel, 1848
Description Male green swordtails grow to a maximum overall length of 14 centimetres (5.5 in), while females reach 16 centimetres (6.3 in). The name "swordtail" comes from the elongated lower lobe of the male's caudal (tail) fin. This species has moderate sexual dimorphism: females are larger than males and lack the characteristic "sword". The wild form is olive green, with a red or brown lateral stripe and speckles on the dorsal fin, and sometimes on the caudal fin too. The male's "sword" is yellow, with a black edge along its lower margin. Captive breeding has produced many color varieties, including black, red, and many combinations of these patterns, for the aquarium hobby. All varieties share the dark-red or brown central stripe. The green swordtail prefers swift-flowing, heavily vegetated rivers and streams, but is also found in warm springs and canals. It is omnivorous, and its diet includes both plants and small crustaceans, insects, and annelid worms.
