Challenges of Reef Keeping – Coral Eaters

Owning a reef tank is a really rewarding hobby, but it can be challenging at times.  Besides keeping the water chemistry in good condition, there are other problems that can harm the coral and cause damage to your reef. There are many different corals and therefore many different pests that may prey on each species.  A lot of invertebrates in the ocean evolve to only eat a specific food item. This is the case for many of the nudibranchs, and many have adapted to be coral eating nudibranchs.  As a reef keeper there is a possibility that you will encounter Zooanthid eating nudibranchs, aptasia eating nudibranchs, soft coral eating nudibranchs, and hard coral eating nudibranchs to name a few. Today, I want to discuss is the soft coral eating type. 

These nuisance nudibranchs (mostly Phyllodesmium sp.)usually attain a size of about a quarter to half an inch, with large ones getting to about an inch. They feed on the tissue of soft corals, such as toadstool or finger leathers, chewing deep canals through the coral or munching on the edges of toadstool leathers.  These nudibranchs can be quite difficult to find because they are usually the same color as the coral, and can camouflage almost seemlessly.  Since they are so small they are able to eat, undetected, by hiding under the coral or in the rock-work near the coral (nudibranchs are usually found not too far from their food source).  The nudibranch may stay hidden during the day and come out at night to feed. 

If you suspect that these annoying creatures have found their way into your tank, the next step is to exterminate them. The best time to find these pests is after your lights have been off for about an hour.  They will be out and active, as well as easier to collect and remove.  You should take extreme care in removing them.  These Nudibranchs have what are called cerata, which are tentacle-like anatomical growths on the upper surfaces of their bodies. When nudibranchs feel threatened they will cast off these cerata, which are extremely sticky. They can adhere to whatever they are touch, usually the coral they are eating. They may carry the eggs of the nudibranch, and new individuals may appear as a result. 

Besides manual removal of the nudibranchs, a coral dip can be a great help in getting a handle on the situation.  An easy method is to use a dipping solution, such as Coral Rx, and “dip” the coral for about 10-15 minutes or according to manufacturer directions.  After the coral has soaked in the solution, give it a good rinse in a clean bucket of water before adding it back to your tank.  The solution also works well on many different pests, including snails, worms, other nudibranchs and other invertebrates, so it can help get ahead of oter potential problems, too.  The dip will not get rid of any eggs that are on the coral, but repeated dips in the days following the initial dips .