News / Species Spotlight / CopyCat - Black Lined Blenny and its Mimic (01/15/15)

CopyCat - Black Lined Blenny and its Mimic

Reef environments are full of fish that use mimicry to one end or another. Some animals look like cleaner fish to try and trick animals into coming close enough so they can have a bite. Other animals will look like a very common animal in their environment so they can hide amongst their numbers. A very common mimicry is one where a fish or other animal looks like something venomous so predators leave them alone. This is the case of the Red Sea Mimic Blenny (Ecsenius gravieri). It is trying really hard to be the Black Lined Blenny (Meiacanthus nigrolineatus) which has venomous fangs which make it a much less desirable prey item than other fishies around it.

Black Lined Blenny (Meiacanthus nigrolineatus)

The Black Lined Blenny is found predominantly in the Western Indian Ocean, including the Red Sea and Gulf of Aden. Among blennies, the genus known as "fang blennies" are likely the boldest. They are usually not bothered by other fish as a result of a wicked set of fangs that pack some venom. Sadly, the same fact that makes these fish desirable (they are in the open a ton) also makes people scared to put them in their tanks. The venom is enough to ward off small predators, but is extremely weak as far as venom goes. It will make the bite site throb, but unless you have a pronounced allergy to things like bee venom, these little guys should give you no reason to fear.

They have been spawned and reared in captivity with methods that are already commonly used in ornamental marine aquaculture. The fry are easy to rear as they hatch out at a pretty big size. The adults are similarly easy to keep as they take prepared foods very readily and are bothered by only the most aggressive of tank mates. If you have always wanted a blenny, these are great choices.

Red Sea Mimic Blenny (Ecsenius gravieri)

What happens if you do have a pronounced allergy to bee stings, and don't want to risk having a venomous fish in your tank? Another fish that comes from the same areas, The Red Sea Mimic Blenny (Ecsenius gravieri), gives you a great option. This fish looks nearly identical to the Black Lined Blenny, but without the venomous fangs. Of course, that also means this fish isn't as bold, and you won't see them as much.

Several fish from this genus have been spawned in captivity, but the fry are much smaller and raising them out hasn't been commercially viable, or at least on a large scale to this point. The adults are pretty easy to keep though, as long as tank mates are chosen carefully. This is a fish that can get bullied and will frequently hide so it is important to house it with fish that won't scare it away from feeding times.

How to Tell Them Apart

This part is actually really easy. While at first glance you see two fish that are yellow and blue with a black stripe, the general shape of both these genus stays pretty constant, and these fish display those traits. Red Sea Mimic Blenny (Ecsenius gravieri) will have a blunt head and be generally thicker as adults where the Black Lined Blenny (Meiacanthus nigrolineatus) has a tapered nose. When you see them side by side, like in the picture below, there are other differences you can pick out like the freckled face on the black line, or the differences in their tail shapes. These are also valid, but the easy one is the shape, if you stick with that, you won't get it wrong.