Emerald crab...

[luvnluk]

Since I've added 3 emerald crabs, I've noticed them scraping purple coraline. What was once solid purple is now covered in white scrapes - I'm sure it will grow back, but are they really eating it?

 

[thomas712]

I've had one do that in the past, and yes he is eating it, by doing so he is also spreading more spores. Take a good look and the scooping claw of his, build for it.
Thomas

 

[clarkiiboi]

I agree with Thomas, that in turn it's spreading the pores. I couldn't (personally) handle the look it was giving to my tank, so I returned it. I worked hard for the coraline to look as it did, and that was a no no in my book. JMO.

 

[thomas712]

Losing color is one thing, having it scraped off is another.
If your coralline is fading, this could be a water problem or lighting.
If it is being scraped off you will know it. It will look etched or like a caustic worm has been crawling on it.
Thomas

 

[goldrush]

Emeralds will indeed eat coraline,but in a good system it's hard for them to keep up with the growth they cause by spreading spores(like Clarkiiboi said). Of course,it depends on how many,but 2-3 in a 55 should be fine.