We recently discovered a tiny nudibranch crawling on the glass of our aquarium. We put it under the microscope and captured this video. Under the blue T5 lights of the aquarium, this nudibranch is highly colorful, fluorescing bright green. The video does little to show this, but you can see how the lighting reflects off his body.
We have determined that this nudibranch is a Zoanthid-eating nudibranch. This may be one of the reasons some of our Zoanthids have been disappearing lately. They are considered pests for this reason, although it is hard to dispose of them because they are so beautiful.
Nudibranchs are a group of mollusks that have no shell past their larval stage. There are thousands of species that are found at all depths all around the world and range in size and variation. Our little nudibranch, with his fluorescent green color, blends very well with our zoanthids, but not all nudibranchs are as colorful.
There are products that I have read aquarists can use in cases of heavy populations of nudibranchs, one of which is Salifert’s Flatworm Exit. This product is said to be safe for fish and invertebrates, but the dead nudibranchs can be toxic to tank inhabitants, so it is important to remove the dead nudibranchs after. Water changes and use of carbon is also recommended. I would definitely recommend research and precaution on any products being used, as many of them are put directly into the tank.
We will keep our eye out for more of them, especially since our Zoanthids have been disappearing. If we find many more we will have to give Salifert’s Flatworm Exit a try.