Aiptasia rock anemones can certainly be harmful to seahorses when they are plentiful . This is because seahorses are demersal animals that orient to the substrate and habitually grasp convenient objects on the bottom with their prehensile tails. This is going to inevitably bring them in contact with any anemones or live corals or sessile invertebrates you keep in the aquarium, so it’s important to avoid anemones and to limit yourself to soft corals and certain select SPS corals or LPS corals that cannot harm the seahorses when they grasp the corals with their tails.
Seahorses are smart and they will learn to avoid an anemone or stinging coral once they’ve come in contact with it. The risk involved in keeping cnidarians with seahorses is therefore twofold, Valerie: (1) the risk that they will be badly stung during that first contact before they realize the anemone is a danger, and that their injury may allow secondary infections to take hold where the integument has been damaged, and (2) the risk from pest anemones (Aiptasia or majano) becoming so numerous that they cannot easily be avoided and that the seahorses repeatedly blunder into them (perhaps after dark or when an unpredictable current whisks the seahorse against the nematocysts). So the greater the number of the anemones confined with the seahorses within a limited amount of space, the greater the risk that they will eventually be severely stung or repeatedly stung, to their detriment.
In my experience, the population of Aiptasia anemones in an aquarium is NOT self-regulating or self-limiting whatsoever. Quite the contrary – they grow like weeds, can reproduce asexually as well as sexually, and can quickly take over an aquarium by sheer numbers. They are not like hydroids, which only become pests in nursery tanks or dwarf seahorse tanks that are receiving daily feedings of newly hatched brine shrimp (Artemia nauplii) that are suitable for filter feeders. The Aiptasia anemones spread by fragmentation and can regenerate an entire individual from a single cell. Aiptasia anemone contain zooanthellae (symbiotic algae cells) and their tissue that give them the ability to produce food via photosynthesis, and they also capable of absorbing nutrients from the aquarium water.
As for removing the rock anemone that’s attached to your seahorse, there are a few different options that work well. You can kill it by injecting it with boiling water or calcium hydroxide, for example. But I think it’s easier just to induce the anemone to release its grip. This is accomplished simply by tapping gently and rhythmically around the base of the anemone’s stalk using your fingernail or any sort of a blunt probe. The anemone may retract at first, but it will eventually relax and begin to release its hold, and as its pedal disc begins to detach from the seahorse you can remove the anemone without any resistance at all.
This technique works because Aptasia anemones have a symbiotic relationship with several species of hermit crabs, which carry the anemones on their shells. The hermits will gather Aptasia anemones whenever they encounter them, inducing the anemones to release their grips on the rocks by tapping the base of the anemones with their claws so that the hermits can reposition them on their shells. The anemones protect the hermits from natural predator such as octopus and box crabs, which benefits the hermits. The anemones benefit in turn by cleaning up scraps from the hermit’s messy meals — in essence, a hermit crab is just a mobile feeding platform for the Aptasia. The rhythmical tickling or tapping is a sort of code the partners in this symbiotic arrangement have developed to allow the heavy-handed hermits to pluck up them anemones and plant them on their shells with their claws without ripping the delicate Aptasia to shreds in the process. So if you can just imitate the tapping of a hermit crab, Valerie, the rock anemone will voluntarily release its grip on your seahorse. It takes a bit of practice, but once you get it down, the tickle technique works like a charm!
if you’re confronted with the heavy infestation of the anemones, then I would suggest that you kill off the largest of the anemones using lethal injections and then acquire several of the small Berghia nudibranchs to control the Aiptasia instead. The Berghia nudibranchs are obligate predators of Aiptasia anemones, meaning that they are specialized feeders and that the Aiptasia anemones are the only thing that they will eat. If they find abundant Aiptasia anemones, the Berghia nudibranchs will reproduce in the aquarium to deal with the abundance of food.
Read through the following article carefully, Valerie – it will explain all about what make Berghia nudibranchs such effective Aiptasia Anemone predators as well as how to care for them and acclimate them to your aquarium properly:
Okay, Valerie, that’s the rundown on the Berghia nudibranchs.
If you haven’t already done so, be sure to check out the following online article as well, Valerie, because it has some excellent suggestions for controlling Aiptasia glass anemones that you may find helpful:
Best of luck getting your Aiptasia rock anemones problem under control.
Pete Giwojna, Ocean Rider Tech Support