Dark brown hard algae?

old_lady_4am · Dec 22, 2022

Hi guys! I have a hard, dark brown/black algae growing in my tank. What is it???

Dan_P · Dec 22, 2022

I have a similar growth but mine is a very deep red which is probably a coralline algae that came from Long Island Sound.

ShepherdReefer · Dec 22, 2022

Very interesting, from many years in the hobby, I have not had this...well, I don't think I have. Unless Dan_P is correct, it might be a simulator for coralline algae.

old_lady_4am · Dec 22, 2022

Oh, didn’t even think about a certain color coming from a certain location! Interesting. Well hopefully it’s harmless. ‍

old_lady_4am · Dec 24, 2022

The hard black/dark brown algae (?) is spreading to other corals now. Should I be worried?

Isiah1820 · Jan 7, 2023

old_lady_4am said:
Hi guys! I have a hard, dark brown/black algae growing in my tank. What is it???

I have the same and trying to figure out what it is.

old_lady_4am · Jan 7, 2023

Sure enough! Well I found out on my instagram account from a very experienced reefer (cc_reefkpr) that it’s black sponge and needs to be kept in check. I’m going to use tweezers to try and remove although I couldn’t even scratch any off so I’m not sure it will work.

Isiah1820 · Jan 7, 2023

old_lady_4am said:
Sure enough! Well I found out on my instagram account from a very experienced reefer (cc_reefkpr) that it’s black sponge and needs to be kept in check. I’m going to use tweezers to try and remove although I couldn’t even scratch any off so I’m not sure it will work.

Ok thanks news to me! And Yea I’ve tried using my nails and it didn’t work. Let me know if you find a way to rid of them or control them. They’ve took over one of my rocks. I remember when they started as a small blotch

vetteguy53081 · Jan 7, 2023

old_lady_4am said:
Sure enough! Well I found out on my instagram account from a very experienced reefer (cc_reefkpr) that it’s black sponge and needs to be kept in check. I’m going to use tweezers to try and remove although I couldn’t even scratch any off so I’m not sure it will work.

try a dental pick or small crochet needle but will work is injecting it via syringe with vinegar. It will shrink the cells for easy removal

old_lady_4am · Jan 7, 2023

vetteguy53081 said:
try a dental pick or small crochet needle but will work is injecting it via syringe with vinegar. It will shrink the cells for easy removal

I’ll try that! Thank you!!

Sfork · Jan 7, 2023

Cover it in epoxy putty

vetteguy53081 · Jan 7, 2023

Sfork said:
Cover it in epoxy putty

Nope. Black sponge often has toxins and the gas bubbles from smothering them will leach them into tank

ISpeakForTheSeas · Jan 7, 2023

old_lady_4am said:
Sure enough! Well I found out on my instagram account from a very experienced reefer (cc_reefkpr) that it’s black sponge and needs to be kept in check. I’m going to use tweezers to try and remove although I couldn’t even scratch any off so I’m not sure it will work.

The sponge that needs kept in check is Terpios hoshinota - an invasive black sponge that grows over and smothers corals (it's very efficient at this, but it can be beaten back/smothered by some corals and coralline algae). I have no idea your specimen here is T. hoshinota or not, but in case it is, I've posted some info about it below as well.

ISpeakForTheSeas said:
They might, yes - as long as the sponge lacks the proper defensive chemicals to combat them (either through killing them or through just being unpalatable to them). Some sponges have toxins, some don't, some toxins are effective against echinoderms (such as urchins), some toxins are not.

Terpios hoshinota contains a couple different cytotoxins which may be a potential deterrent, but at least some sea urchins also have cytotoxic coelomocytes, which to me would seem indicate a chance that the toxins of the above sponge are not toxic to or are only mildly toxic to urchins (I'm neither a toxicologist nor a marine biologist, so I don't know based on the chemistry of the toxin or the biology of urchins if they would be impacted by these specific toxins or not). So, if what you're dealing with is Terpios hoshinota, that would be very interesting to see sea urchin predation on it.

ISpeakForTheSeas said:
I don't know (though it theoretically should be). If it is T. hoshinota overtaking your corals though, it can be killed by shading it* (they shaded it at like 30% natural sunlight for 10 days and found it died and didn't grow back). So, I'd imagine that either reducing your lights or doing a multiday blackout period should be able to kill it.

*The study:

https://www.researchgate.net/publication/318973690_Short-term_in_situ_shading_effectively_mitigates_linear_progression_of_coral-killing_sponge_Terpios_hoshinota