Salty Q&A: Okay to Add LPS to Established Softy Tank?

Question

Hi guys! My husband and I really enjoy your site and the commonsense advice you always give. My question for you is about the feasibility of adding an LPS coral to an established 60-gallon soft-coral tank. We’ve been keeping soft corals successfully for a long time, and now we’d like to give stony corals a try. We’re leaning toward an anchor coral because a friend of ours (who’s moving out of town and has to break down his tank) has a really nice specimen that he’s willing to give us.
Most of the space in the tank is taken up by established colonies, but there is still one rock ledge available that we think should offer adequate room and good conditions for the new coral. The light (T5s) and current should be good in this location, and we’re pretty conscientious about water quality, always keeping nitrates very low.
Is there any reason we shouldn’t proceed with our plans to add the anchor coral (or a different LPS if you think that would be better)? Thanks!
– Submitted by Jackie P.

Answer

Thanks so much for your question and kind words, Jackie! I hate to be a wet blanket, but I’m inclined to discourage you and your husband from making this livestock addition. I say this for a couple reasons: One is your observation that most of the space in the tank is already taken up by other corals and you have only one spot available for the new specimen. What happens if that space proves to be unsuitable for the new coral for one reason or another? You mention that the light and current should be good in that location, but if it turns out that’s not the case, I assume you would have nowhere else to move the coral.

I’m also concerned that you’re underestimating the amount of room you would need for the newcomer. Under the right conditions, the anchor coral you’ve got your eye on (presumably Euphyllia ancora or a closely related species) can reach massive proportions—upwards of 3 feet in diameter. A ledge in the rockwork of a 60-gallon tank just isn’t going to suffice for this species long term.

Also, consider that E. ancora produces long sweeper tentacles that pack a potent sting. That means the ledge it occupies would have to allow enough space to accommodate not only this species’ prodigious growth potential, but also to provide a sufficient “buffer zone” between those stinging tentacles and any neighboring invertebrates.

Now, there are other LPS corals, for example Trachyphyllia geoffroyi, that might fit the available space better and won’t pose a stinging threat to neighbors, but then you still have the question of where to move the specimen if the site proves unsatisfactory. What’s more, owing to their often top-heavy nature and expansive tissues, many LPS corals are better suited to life down on a soft substrate as opposed to perched up in the rockwork.

The bottom line is that having only one viable space available for a new specimen is just too big a gamble—and, to be fair, not just for LPS corals. On many occasions, I’ve placed invertebrate specimens in locations that would seem ideal only to have them “sulk” until I move them somewhere else.