Elacatinus colini
A small goby with a bright white stripe, symbiotic with sponges.
The Belize sponge goby, Elacatinus colini, lives in the Western Central Atlantic Ocean around Belize and Honduras. Its species name honors Patrick L. Colin, who studied the Elacatinus genus for his doctorate. This fish was once mistaken for a color variety of Florida’s Elacatinus xanthiprora, but it became recognized as a distinct species because of its bright white stripe instead of a yellow one. Adults reach about 3 cm in length (males up to 3.2 cm standard length, females up to 3.4 cm). A white stripe runs from head to tail; on the head, this stripe is roughly as wide as the pupil, but along the body it widens to about the eye’s diameter. The fish has 8 dorsal spines, 10–12 dorsal soft rays, 1 anal spine, 10–11 anal soft rays, and 17–19 pectoral rays. It lacks scales and is coated in thick, sticky mucus. The body above the lateral stripe is bluish-greenish gray, while the top of the head, iris, and lips are bright yellow, and the underside is white. Fins are translucent gray.
These gobies live in marine systems, sheltering inside various sponge species in a symbiotic relationship. They have been recorded at Carrie Bow Cay in Belize and Utila Island in Honduras, inhabiting shallow sponges at depths of 2 to 17 meters, possibly deeper. Their tropical range lies between 17°N and 16°N, 88°W and 89°W, covering roughly 11,184 km². The population seems abundant locally, though little data exists on trends.
A study on diet found that E. colini larvae survived better and grew longer when fed wild-caught plankton rather than rotifers or brine shrimp (Artemia). Researchers suggested the larvae might lack the ability to digest Artemia and rotifers, or that Artemia could alter water quality or deplete oxygen, though the last idea was considered unlikely since tanks were well oxygenated.
In reproduction studies, both sexes turned dark gray or black before spawning. Spawning occurred 3 to 44 days after introduction to tanks—faster than in Elacatinus lori—and clutches were relatively small. Spawning happened every 7.8 ± 1.7 days over a 12-month period. Males incubated eggs by fanning and mouthing them until hatching; females sometimes ate the larvae afterward. Embryos hatch with a fully functional mouth, inflated swim bladder, pigmented eyes, and two visible otoliths.
Quick Facts
- Common name
- Belize sponge goby
- Maximum length
- 3.4 cm SL (female), 3.2 cm SL (male)
- Distribution
- Western Central Atlantic Ocean, near Belize and Honduras (17ºN–16ºN, 88ºW–89ºW)
- Depth range
- 2–17 m
- Conservation status
- Least Concern
Facts from the source article.
Lore & Background
Elacatinus colini was originally considered a color variant of Elacatinus xanthiprora, but it was reclassified as a distinct species due to its bright white stripe (as opposed to yellow). The species is named after Patrick L. Colin, of the Coral Reef Research Foundation, Palau, who studied the genus Elacatinus for his doctoral thesis. The goby is bluish-greenish gray above its lateral stripe, with a bright yellow dorsal head, iris, and lips, and a white ventral body. Its fins are translucent gray. The lateral stripe on the head is about the width of the pupil, widening to the width of the eye on the body. The fish lacks scales and is covered with thick adherent mucus. It typically has 8 dorsal spines, 10–12 dorsal soft rays, 1 anal spine, 10–11 anal soft rays, and 17–19 pectoral rays.
Reader's Guide
Elacatinus colini lives in marine systems in symbiotic relationships with various species of sponges, using them as shelter. It has been found at Carrie Bow Cay in Belize and Utila Island in Honduras, inhabiting shallow sponge habitats between 2 and 17 m deep, though it may live deeper. The species occupies an area of about 11,184 km². In a study, larvae survived in higher numbers and grew to a larger standard length when fed wild-caught plankton rather than rotifers or Artemia; researchers hypothesized that larvae may not digest Artemia and rotifers well, or that Artemia could affect water quality or oxygen levels, though the last was considered least likely. Before spawning, both male and female bodies turn dark grey or black. Spawning occurred within 3–44 days of introduction to study tanks, with clutches smaller than those of Elacatinus lori, and spawning every 7.8 ± 1.7 days. Males incubated eggs by fanning and mouthing until hatching; females sometimes consumed larvae after hatching. Embryos hatch with a functional mouth, inflated swim bladder, pigmented eyes, and two visible otoliths. Larvae swim toward light and feed on rotifers starting about 12 hours after hatching. The white stripe develops immediately after settlement, while yellow pigment on the snout takes a few days. No current threats are observed, but degradation of sponge habitats could negatively impact the species. Monitoring is recommended, and the species is categorized as Least Concern.
Did You Know?
- Elacatinus colini was originally thought to be a color variant of Elacatinus xanthiprora but was reclassified due to its bright white stripe.
- Before spawning, both male and female Elacatinus colini turn dark grey or black.
- Larvae of Elacatinus colini survive better and grow larger when fed wild-caught plankton rather than rotifers or Artemia.
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