giant jawfish
Opistognathus rhomaleus
Jawfish of sand and gravel bottoms, from Baja California to Costa Rica. It is usually caught by trawlers and by anglers with rods.
Also called: boca-grande, bocón gigante, giant jawfish
- maximum
- 51 cm
who is the giant jawfish
The giant jawfish is a fish of the family Opistognathidae, living on sand and gravel bottoms in the eastern Pacific, from Baja California and the Gulf of California to the Revillagigedo Islands and Costa Rica. It reaches 51 cm, more than the spotted jawfish, which reaches 40.6 cm. Like other jawfishes, it digs burrows and hides in them. It feeds on benthic and planktonic invertebrates. It is little sought, but is usually caught by trawlers and by anglers with rods.
Essential profile. Identification, where it occurs and rules, with data from FishBase and the cited regulations. Season, time of day, technique and bait are added once we have a good source for the giant jawfish; in the meantime, see the similar species.
fun facts
- It is bycatch from trawlers.
identification
Jawfish with an elongated body, a large head and a wide mouth. It is bigger than the spotted jawfish (Opistognathus punctatus): it reaches 51 cm, compared to 40.6 cm. It lives on sand and gravel bottoms, in burrows it digs. The size difference helps tell apart the two species, which share the same coast and have the same general shape.
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Each card shows the day's index (0 to 100) and, below it, a strip with the index for each hour, from 0h to 23h. from poor to excellent.
Essential profile: the index uses a general fish model (weather, sun, moon and tide), without a season or time of day specific to this species.
where found
In Latin America it occurs from Baja California and the Gulf of California to the Revillagigedo Islands, in Mexico, and as far as Caño Island, in Costa Rica, on sand and gravel bottoms.
Habitat: Sand and gravel bottoms, where it digs burrows.
rules for the giant jawfish
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency.
We found no species-specific rule beyond the region's general rules.
catch and release
catch and release Releasing the fish alive, quickly and with a wet hand. During a closed season it isn't always allowed: what the regulation says applies.
It has no spines or venom. Release it carefully and without squeezing the body.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00389, b = 3.12; FishBase (relação peso-comprimento bayesiana, estimativa)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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sources and references
Essential profile: size, length-weight, depth, countries and conservation come from FishBase and the cited regulations, and the texts were written from those sources. Season, time of day, sensitivities, technique and baits and lures are not included yet, because we did not find a good source for this species.
- scientific FishBase: Opistognathus rhomaleus (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Opistognathus rhomaleusNames by country and language.
