Sargassumfish, Histrio histrio

Sargassumfish, Histrio histrio. Fish caught from coastal waters off Boca Raton, Florida, March 2024. Length: 9.7 cm (3.8 inches). Catch, photograph and identification courtesy of James Lafontaine, Long Island, New York.

Sargassumfish, Histrio histrio. Underwater photo taken at South Padre Island, Texas, May 2010. Photograph courtesy of Ruben Gonzalez, South Padre Island, TX.

The Sargassumfish, Histrio histrio, is a member of the Frogfish or Antennariidae Family, and is known in Mexico as pez sargazo. It is one of the more exotic and most unusual fishes in the world. Globally, this is the only species in the genus Histrio, which is found in Mexican waters of the Atlantic Ocean.

The Sargassumfish has a somewhat compressed globular bodies with a laterally flattened body. They are pale cream to greenish dark brown in color with fleshy weed-like appendages that make them resemble and blend in with the Sargassum Algae for which they are named and within which they live. They have smooth skin and lack the dermal spines found in other members of the family. Their head features an upturned mouth and a bulbous tipped illicium over the margin of the eyes that is continuous with the body.

The Sargassumfish is found in marine habitats at depths between 9 m (30 feet)  and 15 m (50 feet) and spend their entire life associated with floating sea grass beds, mostly Sargassum Algae. They reach a maximum of 20 cm (7.9 inches) in length. They are preyed upon by sea birds and larger fish but can avoid larger fish by jumping out of the water and onto floating seaweed. They have 2 distinct sexes with the eggs generated by the females in a gelatinous floating mass that the males inseminate through external fertilization. The Sargassumfish is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Sargassumfish is found throughout the tropical and subtropical seas of the world including the Atlantic Ocean, Indian Ocean, the Red Sea, the Western Pacific, however, they are absent from the Eastern Pacific Ocean. It is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.

The Sargassumfish cannot be confused with any other species due to its appearance.

From a conservation perspective the Sargassumfish is currently considered to be of Least Concern with stable, widely distributed populations. They known to contain ciguatoxin and are thus not recommended for human consumption. They are sold commercially via the aquarium trade at a modest level.