How easy are sea fans to keep?

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A reader wonders how best to keep sans in his reef tank. Jeremy Gay advises..

Q) I’ve recently seen some sea fans for sale, which would look amazing in my 400 l reef tank. I keep mainly LPS corals and they’re doing very well. But at £35-£40 each I don’t want to buy these sea fans if they won’t survive. I have a Yellow Tang, a Pyjama Wrasse, a Royal Gramma, two Percula Clownfish — no dwarf angels or anything ‘nippy’. Inverts are snails and reef hermits and a Peppermint Shrimp that I rarely see. Would the fans need any supplementary feeding?

CHARLIE ELLIS, VIA EMAIL 

A) Jeremy advises: Sea fans vary from being as easy as a Leather Coral to harder than the most sensitive Acropora. This is because there are two main types: photosynthetic and non-photosynthetic, often abbreviated online to NPS. Photosynthetic gorgonians (sea fans,) only require medium light and flow, and
no special feeding. Their polyps are on the whole brown/grey, but their long branches still make them excellent additions to a reef tank where they provide that maritime look.

If the sea fan has bright polyps like yellow, pink, purple or blue, it’s a non-photosynthetic gorgonian, and although very visually appealing, they are almost impossible to keep. In nature, they live at depth, or in turbid water or caves, and don’t receive any nourishment from symbiotic photosynthetic algae in their tissues. Instead, they use those polyps to capture zooplankton very regularly throughout the day. They often live in unidirectional flow and are exposed to a rich soup of food particles that is virtually impossible to simulate in a reef tank. Placed in the light, in a clean tank, they will starve and die. So, the answer is ‘yes’ to brown sea fans but a definite ‘no’ to any colourful ones!