There are more than 900 known species of blenny fish, with dozens of species common to the aquarium hobby. They vary significantly in color, with one genus containing blennies with venomous fangs! Once they have the fun cave to call their own, blennies are a peaceful addition to the community’s many well-secured saltwater tanks.
Origin and Distribution
There are many different genera and species of blenny. The “true” Blennii are members of the order Blenniiformes. They are found in many areas of the world and in recent years several species have now been allowed to be bred in captivity.
The genus Meiacanthus consists of species of venomous blenny. They have venomous fangs which they use for self-defense. If you have this species, please pay attention to your blennies when cleaning the tank or moving decorations. Never let children put their hands in the tank and never hand feed them.
Colors and Signs
Blenny colors vary widely. Most blennies have elongated bodies and many use their pectoral fins as supports to rest on the bottom of your tank and trim.
Depending on your blenny species, they may be one color throughout, such as the Canary Blenny, or have brindle colors to blend into their background, such as the Sailfin Blenny. Unlike other common reef species, the blennies may be dark or light in color pattern.
Blennies are semi-aggressive fish and do well with many other semi-aggressive community coral species. They are safe from corals but often hunt small plankton living on algae surfaces and live rock.
Blennies like to have territory to call their own, so they don’t do well with small, like-minded species, such as dottybacks and damselfish. They will use their venomous fangs on their tank mates if they are scared or stressed. Once they have a happy home, they usually become very easy-going community tank mates.
Blenny Habitat and Care
For happy blennies, it’s important to provide them with lots of little nooks and crannies. Because they are small, they will not compete for larger caves with semi-aggressive big fish. You may see your blenny dig their own cave under rocks and rock live through their gravel or sand.
As with all saltwater systems, proper water quality is critical to fish health. Follow a regular maintenance schedule, keeping in mind that your blenny may be hiding in your cleaning area. Especially with venomous blennies, you need to know where your fish are hiding!
Blennies have been known to jump out of their tanks, so a well-fitting lid is essential. Don’t discount their small size thinking they won’t jump from their high resting place on a frieze during rearing or feeding.
Thankfully, blennies aren’t known for being picky eaters. They do well with many saltwater community diets. Certain species of blenny may fall more toward the herbivorous or carnivorous end of the fish spectrum, but the vast majority are omnivores.
Venomous blennies forage more in the middle of the water column compared to other species of blenny which focus on bottom feeding. For most saltwater community tanks, broadcast feeding over a large area of the tank is best for ensuring that everyone gets enough food without too much competition.
Some blenny species, such as the Sailfin Blenny, are sexually dimorphic in coloration, with the males being darker than the females. But for many species, there are no obvious external cues. Sometimes, female blennies are larger than males, but this is not a uniform rule.
Since it is difficult to determine a male vs female blennies, it will be very difficult to start a breeding program. They can form harems, with one male reproducing with several females, so it is advisable to add a few individuals to the breeding tank, provide them with lots of caves and crevices, and let them form their own groups.
One male blenny may mate with one or several females. After the female has laid her eggs, the male may care for them in the same nest. Larvae hatch within seven to ten days and require supplementation while remaining in the breeding tank.