Scientific name: Hoplias malabaricus
Other names: Tararira, Tarucha, Trahira, Traira, Tarango
Distribution: It is a native South American species.
Weight and measures: The size depends on environment condition; however, the average size can go from 1 to 7 pounds and 28 inches long.
Habitat and life cycle: This species lives in river and lake environments. It prefers shallow, warm and murky waters with abundant vegetation. During winter season it goes through a period of lethargy, feature that makes it thin and hungry by mid spring. In summer to early fall they feed voraciously to build up reserves for the next winter.
As their habitat tends to have low proportion of oxygen, wolf fish have the ability to breathe air by positioning its dorsal fin above water, which takes a reddish color indicating that gas exchange is occurring by diffusion.
It is an oviparous species. Spawning period is extensive, up to five months, beginning in spring. Breeding specimens prepare the redds in shallow water, and once females lay the eggs, these are guarded by the male. Both male and female alternate to oxygen the nest, and conscientiously guard their young.
Appearance: This species has a cylindrical body covered with thick scales and a large amount of mucus, which protects them against external parasites such as leeches. Their muscles are adapted to short and fast swimming, and as any predatory fish, they have a large mouth with powerful teeth, even on the palate. Their head is large and well ossified.
Wolf fish color ranges from dark on the dorsal side to iridescent with spots on both sides, fading to whitish-yellow on the belly. Coloration may vary as a consequence of the pigment cells, called chromatophores, which they have all over their body. These cells are units that respond to guidelines imposed by the external environment (temperature, transparency and salinity of the water) and internal environment (irritability).
Diet: Wolf fish are instinctive hunters. On their first stage they feed on the yolk sac, and afterwards they start preying on different aquatic microorganisms, fry and juveniles of other species. Their adult diet is based on fish, amphibians, insects, rodents, birds and animals. Anything that could cause some vibration on the water may trigger its predatory instinct.