What Salt Water Aquarists Need to Know About the Berghia Nudibranch

Berghia nudibranchs are species of sea slug that can be raised in salt water tanks. These graceful creatures are also helpful, eating the pesky aiptasia or glass anemones.

Once upon a time, keeping a salt water aquarium was a dream, unless you were incredibly rich. And then the Nano cube was developed and such things like live rock and live sand and suddenly keeping healthy a reef tank as small as a half gallon was possible. But one problem arose from the mostly beneficial live sand and live rocks - aiptasia anemones, also called glass or rock anemones.

It took a few years, but several species were discovered that not only would eat aiptasia but could be kept in tanks of under 100 gallons large. One of the most touted and graceful is a group of sea slugs known as Berghia nudibranchs and in particular one species known as Berghia verrucicornis. Some people claim that they are the best aiptasia control method available.

What Does It Look Like?

Don't let the common name of sea slug make you squirm. These are tiny critters, often less than an inch long (25 cm) when fully mature. A nudibranch (pronounced NOO dee brahnk) is often brightly colored and covered with feathery fronds. A Berghia nudibranch is pearly white, but often has some pale gold or beige coloring in its cnidosacs or fronds. Berghia nudibranchs tend to change color depending on what color their food was. Since many aiptasia anemones are brown, that may be the most popular color among the well dressed nudibranches in the tank.

Berghia verrucicornis originated in the shallow waters of the Carribean. They were discovered eating anemones and by the 1990s studies were being done to see if this could be an effective means to control the weed-like aiptasia anemone. By 1996, the American Zoo and Aquarium Association (AZA) were beginning to use Berghia nudibranchs in massive public aquariums. By 2000, the home aquarist could purchase and use them for their much smaller tanks.

Advantages

There are several advantages to keeping Berghia nudibranchs in your reef tank or in a refugium if the rank already is home to seas slug eating critters. The first is that they are so small. They do not lead a lot of space, unlike large anemone eating fish such as the copperbanded butterflyfish (Chelmon rostratus), which can grow up to eight inches long.

The second is something AZA likes: Berghia verrucicornis can survive in tanks with bright light, but it does have a tendency to prefer crawling about in dark spots. They get along with micro starfish, cleaner shrimp and other small ornamental shrimp species.

Because of their soft bodies, Berghia verrucicornis can get into cracks and crevices that other anemone eaters like peppermint shrimp (Lysmata wurdemanni) cannot get into. There are some advantages to not having a skeleton.

Disadvantages

There is conflicting information about how to care for Berghia nudibranchs. Since this is such a new wet pet, most of the information known comes from people who breed and sell them as opposed to fish care books or magazines written in everyday language. It is also unknown just how long they are supposed to live. Some aquarists say six months - others over a year. And, as you might expect for a critter so useful - it is expensive.

Nudibranchs can be killed by filter equipment, jellyfish, many fish, carnivorous crustaceans and inept handling. They should not be touched by people because they are delicate. They need time to acclimate to a new refugium or tank, although Anthony Calfo, writing for "Reefkeeping," claims they can be kept in jars or beakers about 500 ml large.

Perhaps the biggest disadvantage is their diet. If the tank runs out of aiptasia, then you are soon going to run out of Berghia nudibranchs.