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Seaweed Blenny

Parablennius marmoreus

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Original side-profile illustration of Seaweed Blenny (Parablennius marmoreus); look for a blenny with a long, branched cirrus above each eye, delicate blue lines descending from the eye, and an eyespot near the front of the long dorsal fin.
Original identification illustration of Seaweed Blenny. Features may vary.

Fun facts for your next surface interval

  • Some seaweed blennies are entirely yellow rather than mottled brown.
  • Youngsters sometimes ride floating Sargassum instead of remaining on a reef.
  • The blue lines beneath the eye and lack of nape tufts can identify a fish whose body color has changed.

Florida and local context

Lake Worth Lagoon, Palm Beach County, Florida: The exact species row in the Florida Museum Lake Worth Lagoon checklist is marked verified, rather than merely listed as potentially occurring.

Documented regional presence is not a guarantee of an encounter or a measure of how common this animal is at your dive site.

How to recognize this animal

Look for a blenny with a long, branched cirrus above each eye, delicate blue lines descending from the eye, and an eyespot near the front of the long dorsal fin. There are no cirri on the nape. The body can be tan, reddish, orange or yellow, and spots sometimes merge into a dark horizontal stripe.

Size and life stages

The Smithsonian account gives a maximum length of about 10.8 cm (4.3 inches). Its reported depth envelope is 0–35 m. These are species-level limits, not the expected size and depth of every encounter. Use markings and proportions as well as apparent length; a photograph without a reliable scale cannot establish an exact measurement.

Habitat and where to look

Rocky reefs with algal growth are the principal habitat. Young individuals also occur with floating Sargassum, so the common name describes more than one sort of association with seaweed. Around hard substrate, inspect small ledges and crevices without disturbing the algae. Floating material should be observed in place rather than lifted aboard for an identification photograph.

Range and local context

The documented regional range is New York south to southern Brazil. The exact species row in the Florida Museum Lake Worth Lagoon checklist is marked verified, rather than merely listed as potentially occurring. These records establish geographic occurrence, not abundance or a guaranteed encounter at a particular dive site.

What is on the menu?

The Smithsonian diet record describes an omnivore that takes algae as well as small benthic animals. Recorded categories include worms, small mollusks and attached organisms such as hydroids. Its single rows of jaw teeth and rear canines differ from the tooth arrangement of many sand gobies. Grazing or picking at a reef surface can therefore involve more than one food type.

Daily habits and behavior

Color variation is an important part of this species rather than an exception to the identification. Some individuals are yellow; others have clustered brown spots, or strong pale and dark stripes. Juveniles traveling with Sargassum inhabit a very different setting from adults on a rocky reef. Record the visible pattern and habitat instead of expecting one fixed color.

Mating and the next generation

It produces benthic eggs, while the larvae enter the plankton. That reproductive pattern separates the early dispersing stage from the later reef-associated stage. The accessible species sources do not establish a Palm Beach spawning calendar, clutch size or incubation period, so none is inferred here. An adult in a hole is not by itself evidence of a nest.

Look-alikes and identification traps

Molly millers can have a similar olive or spotted appearance, but they possess conspicuous rows of nape cirri. Seaweed blennies lack those nape tufts and show their own combination of long eye cirri, blue cheek bars and a front-dorsal eyespot. Small gobies usually have two distinctly separate dorsal fins, whereas this blenny has one long dorsal with little interruption.

Observe without disturbing

Photograph the head and the front of the dorsal fin when the animal naturally exposes them. Avoid pinning algae aside, handling Sargassum or removing the fish from a crevice. Blue cheek lines can be difficult to see in ambient light, so make a brief, nonintrusive photograph rather than repeatedly chasing it for a brighter angle.

Harvest, protection and eating safety

Restricted marine life: live collection only; no spearing

Can it be hunted or harvested?

Seaweed Blenny (Parablennius marmoreus) is regulated tropical ornamental marine life, not an unrestricted food-fishing species. FWC lists blennies in family Blenniidae. Where collection is lawful, a saltwater fishing license is required unless exempt. Land and keep the fish alive with circulating, aerated or oxygenated life support. No species-specific recreational size limit is listed. Daily limit: five of this species within 20 marine-life organisms total per person. Two-day possession maximum: ten of this species within 40 organisms total. Recreational sale is prohibited.

Florida seasons and areas

No annual recreational closed months are listed for this marine-life species. Collection is prohibited within the designated Blue Heron Bridge dive-site boundary and throughout Biscayne National Park. Collection of these gobies and blennies is also prohibited in John Pennekamp Coral Reef State Park. Florida marine-life rules also apply in adjacent federal waters on both coasts. Check the exact park, refuge or sanctuary zone before collecting. The designated one-square-mile Western Dry Rocks area is closed to all fishing April 1–July 31 annually.

Can it be speared?

No. Spears are not authorized recreational gear for this regulated marine-life fish. Only lawful live-collection methods may be used, such as permitted hand-held, barrier or drop nets or a slurp gun. The live-landing requirement still applies.

Is it safe to eat?

Not recommended as a food target. This fish is regulated for live collection, and this guide does not certify it as safe to eat. Check Florida DOH guidance before consuming locally caught fish. Cooking does not remove all marine toxins. Small size, an absence of a specific advisory, and lawful collection do not establish food safety.

Before you act: This recreational overview is not permission to collect or spear at your dive site. Confirm the species, date, management area, state or federal waters, gear, licenses and current local closures. Identification artwork cannot establish an identification or guarantee seafood safety.

Official rules and health guidance

Reviewed 2026-11-10. Rules and advisories can change; check the linked authorities before harvesting or eating.

Sources and review

Reviewed 2026-11-10.

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