No fish No problems

[Bugger]

Can corals live with a complete lack of fish? Or will the zoox run into a problem?

[tmz]

Yes , if you feed them. Photosyntesis via zooxanthelae alone will not sustain a coral long term; if that's what you are asking.

[JSeymour]

They can be, but fish add movement and help keep your corals and live rock healthy. Fish provide many beneficial services to your tank, from feeding corals(feces) to eating pests(parasitic flatworms, aiptasia, pyramid snails, algae, etc). At one point, I did keep several reef tanks without fish to keep nutrients low. I had several problems. The biggest problem was keeping the corals fed well enough. Over time, they started getting very pale due to undetectable nutrients levels for prolonged periods. I started feeding small amounts of various corals foods. Because the tanks were so clean, even the smallest amounts of food would cause major algae issues. After struggling back and forth with pale corals and algae blooms, I decided to start adding fish. At first due to food being added now on a regular basis, algae started to grow, but not as bad as before with no fish. Shortly after, my copepod numbers increased substantially, sponges started growing, and the algae decreased. Along with this, my corals began showing more polyp extension, brighter colors, and more growth.

So can you grow corals without fish? Sure, but it's much easier to starve or overfeed your corals without them.

[bertoni]

I ran fish-free tanks for years with no problems. Just feed as appropriate for the coral species in the tank... :)

[JSeymour]

I struggled, seems easier with fish. Of course I know a lot more than I did years ago...