longspine grunt
Rhencus macracanthus
Grunt of coastal waters and estuaries in the eastern Pacific, which also lives in brackish water. It is sold fresh and commercially fished.
Also called: roncador-espinhudo, roncacho gordo, roncador ruco, longspine grunt
- maximum
- 37 cm
- depth
- 1–30 m
who is the longspine grunt
The spiny grunt belongs to the family Haemulidae, the grunts. It reaches 37 cm, and its common size is 20 cm. It lives in the eastern Pacific, from Mexico to Ecuador, near shore, between 1 and 30 m deep. It enters estuaries and lives in brackish water. The body is oblong, moderately compressed and somewhat deep, with a small, terminal mouth. Commercial fishing takes it, and it has little presence in sport fishing.
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 longspine grunt; in the meantime, see the similar species.
identification
Oblong body, moderately compressed and somewhat deep, with a small, terminal mouth. The back is dark brown or grey and the belly silvery. The back and flanks have four or five faint dark bars, sometimes absent. The dorsal and anal fins have a sheath of scales at the base. It can be confused with Rhonciscus branickii, which also enters estuaries and lives on sandy bottoms near the coast.
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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
Found in the eastern Pacific, from Mexico to Ecuador, in coastal waters, estuaries and brackish water.
Habitat: Near shore, in estuaries and brackish water, from 1 to 30 m.
rules for the longspine grunt
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.
No danger to anglers. If released, return it to the water carefully.
in the kitchen
Sold fresh in markets.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.01318, b = 3.06; FishBase (relação peso-comprimento bayesiana, estimativa da própria espécie)). 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: Rhencus macracanthus (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Rhencus macracanthusNames by country and language.
