Mexican Mojarra

Fascinating facts about the Mexican Mojarra

• It was first recorded from Everglades National Park, Florida, in 1983, and is now a common nonindigenous fish in South Florida.
• Even though it prefers water with at least 3.5 mg/L dissolved oxygen, the fish can survive virtual anoxia for up to two hours by slowing down.
• With a jaw that can protrude 6.8 % of its length, it can snatch about one-fifth of the fast-moving prey that other fish miss, turning a modest bite into a potent hunting tool.
• In its native range the species breeds for nine months, from March to November, and can raise several broods a year, guarding the fry for up to six weeks.
• It can tolerate salinities from fresh water up to 40 ppt and abrupt jumps of 15 ppt, allowing it to move from inland rivers into brackish lagoons and survive brief marine spells.

At a glance

About the Mexican Mojarra

The Mexican mojarra, Mayaheros urophthalmus, is a strikingly large cichlid that can reach nearly 40 cm (15.5 in). Its oval, laterally flattened body is painted in a yellow-brown to gray-brown base, overlaid with six wide green-black vertical stripes that run from the pectoral to the caudal fin. During breeding the whole fish blushes intense red, and a conspicuous black eye-spot circled in blue-green crowns the tail stem, a nod to its name meaning “tail-eye.” This versatile predator inhabits a mosaic of freshwater marshes, mangrove swamps, lakes, rivers, rocky shores, lagoons, estuaries and even coastal islands across the Atlantic slope of tropical Mesoamerica, from eastern Mexico to Nicaragua, and it has colonised the Everglades of Florida since its first record in 1983. It thrives in oxygen-rich waters but can endure extreme hypoxia, becoming nearly inactive and surviving virtual anoxia for up to two hours, a rare feat among cichlids. A true generalist, it grazes on algae, detritus, snails, crustaceans, insects and smaller fish, relying on a modest 6.8 % jaw protrusion to snatch evasive prey. Its territorial breeding pairs guard multiple broods on substrate for up to six weeks, with fry immediately sinking to the bottom and adhering via mucous glands, a behavior that readies them for the swift currents of their native streams.

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