How long can corals survive without light.

[Anemesis]

This is personal experience, that happened to me. Found a friend i hadn't heard of for months and was beginning to worry. He doesn't live near by ; i found him lying in **** half dead in his home, his dog had poop all over and the man was in a depression.


After taking care of him, hospitalized and all , we friends and i went to his basement to check is 5 tanks. A horror show if i ever saw one. some fish were alive still, but just. Our calculation brought us to 2 months. for some reason the light weren't working and we found out later that his fuse had burned out and he didn't give a damn.He was near suicidal the doctors told us.

For 2 months some coral survived the darkness , about 4 nems bleached by now but we rescued them with the fishes 3 died the other 4 fish survived. Tangs all of them . one carpet nem, 2 rock nem and we're not sure about the other it died. the strangest thing was the algae in one of the tank survived and over grew the tank trapping 2 clowns that dies later. We figure a small window that you find in old houses was the light source for it.


As for the other tank, the parameters were not that crazy. main elements were still there, Cal, Mg we didn't do all the test we just made a clean up and took the rest home.

The orp was way below the norm, Phosphate, nitrate off the scale, we found lost of inverts well and alive. The skimmer was over flowing but in a drain which he had installed in his set up. We found one of his giant clam dead of course full of worms yuk, and the clowns barely moving but alive for a while.

None of the hard coral survived only the hardiest soft and LPS, the NPS were surprisingly fine actually. Nudibranch, urchins,were fine, none of the starfish were found for obvious reason.

Anyway for some who wonder how resilient our tank mates are that gives you an insight.About 2 months without any care some did survive, i imagine a month would be fine. That's an assumption of course.

[CrayolaViolence]

Depression is a hard illness that very few people understand. Kudos to you for helping without judgment. Thank you.

As for no light. Remember corals eat too. If there were enough nutrients and air in the water for the corals, then they can probably go for quite some time. I've had a few frags fall under rocks not to be found for months, and had them survive. Some of which were acropora. Not always, but sometimes. And some of the spaces under my rock work are total darkness (or were till I opened it up some.)

[Ron Reefman]

I agree, corals and lack of light is a VERY individual thing. How healthy is the coral at the start, how much light was it getting, how much food is in the water supply, how well can it collect food from the water... every coral is a bit different.