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Blennies: A curious fish with a venomous bite!

Bicolor Blenny (Ecsenius bicolor)

What is a Blenny?

The Blenny, or Blenniidae, is an unusual fish. With over 900 species, they boast an amazing assortment of colorations. Some, like the Canary Blenny, have one color throughout, while others, like the Sailfin Blenny, have a mottled color to help them blend into the background. Most Blennies have elongated bodies and, just like Bichirs, have pectoral fins that help them rest at the bottom of the tank. One Blennies genus even contains venomous fangs. Any Blenny would make an amazing addition to your aquarium.

How big is a Blenny?

A Blenny can grow to between three and five inches when fully mature.

Tail Spot Blenny (Ecsenius stigmatura)

What size tank and conditions do Blennies need?

Blenniidae are fairly small and require a minimum tank size of 30 gallons. To keep your Blennies happy, provide lots of tiny nooks and crannies in their tank. Smaller Blennies will not compete with larger, more aggressive fish for these caves, preferring instead to find an unoccupied cave or dig under rocks and through sand.

Blennies are marine fish, so maintaining optimal saltwater conditions is absolutely critical. Regular tank maintenance is important, as well as fitting your tank with a lid, as they are active fish known to be jumpers. There is a venomous genus of Blennies, so care must be taken when handling those fish.

Sailfin/Algae Blenny (Salarias fasciatus)

What do blennies eat?

Blennies are not picky eaters, making them ideal for home aquarists. Most Blennies are omnivores, but some species may be more inclined to be herbivores or carnivores. Most Blennies feed on the bottom of the tank but venomous Blennies tend to forage more in the middle of the water column, so it is best to scatter the food across the tank to ensure that all your Blennies get their food without having to compete for it.

Are blennies venomous?

One of the most amazing facts about Blennies is that they have countless variations and even contain a genus with venomous fangs.

While most venomous fish inject venom through their fins, Blennies tend to deliver theirs through a swift, venomous bite. When tested on mice, research found that their venom does not produce pain, but instead causes a sudden drop in blood pressure. This suggests that their bite might cause a stupefying effect on potential predators who might try to make a quick meal of a Blenny. As such, venomous Blennies need to be managed with care.

Molly Miller Blenny
Molly Miller Blenny (Scartella cristata)


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