Emerald Crab and Royal Gramma

[TheTman22]

Hey Ladies and Gents,

So I've had a freshwater tank for 15 years that I recently ended and wanted to go to the next level and start a small reef tank. Everything has been going well with the exception of a ph drop that was handled and building up calcium however something strange happened today. I had a Royal Gramma on Friday this week that was eating and coming out of his hiding place and seemed in general fine. However, I came back from a weekend trip on Sunday to see my Emerald Crab and 2 hermit crabs eating what was left of him. I was pretty upset because he was only my second fish and he was starting to become a worthy addition after a few weeks of barely coming out at all. I don't know what happened and I'm concerned that my Emerald Crab killed him while he slept in the rock. It worries me more because my clownfish sleeps on the sand because I don't have a suitable coral in which for him to host for security. I know if Pennywise the Clownfish is killed my wife will be very sad as it is her absolute favorite fish I've ever had. Is there a chance that the crab killed the gramma and if so, what would be the best solution to protect the clownfish?

[ramseynb]

It’s likely that the fish died and they were eating the leftovers. However, crabs are opportunistic and should never be fully trusted. Do they have sufficient algae in the tank to eat?

[Uncle99]

I banned every crab regardless of there supposed safety 18 months ago now.
Since then I have not lost a coral, a fish or even 1 snail.
I did this because I caught a red legged hermit, walking around with a prized clown in its claws.
All crabs to me are opportunists and if they can catch it they will eat it. Period.
People told me it was my fault because I should have fed them, garbage....I do not need them in my CUC because I provide perfect water consistently and have no algae for them to eat. I do keep snails, but nothing else.....18 months since...not one loss.....beware!

To me, having crabs as a CUC is a myth, the amount of clean up they do is minimal, I found I could pick any small pieces by hand in 2 minutes, I spend most of my time making sure it does not develop, by regular hand maintainence, great water changed weekly, a balanced photoperiod if only 9 hours.

A small toothbrush beats any CUC!

In my latest rebuild, 5th in 25 years, I decided only to put in the tank, fish, lots of corals, shrimps, and snails....no others allowed.....no stars, no brittles, no cucumbers, No Crabs.

What a peaceful place my tank is....nobody bothers nobody.....just great colour and fish that stay out all the time and do not have to worry about night predators....

Not as worried about the emerald, but the hermits to the sump.

[Tripod1404]

Originally Posted by Uncle99

Since then I have not lost a coral, a fish or even 1 snail.
I did this because I caught a red legged hermit, walking around with a prized clown in its claws.

Lol that is impossible in so many ways. A fully grown red legged hermit is smaller than a baby clown. You introduced a non reef safe hermit and failed to identify it correctly. And that is your fault to not being able to identify it.

Originally Posted by Uncle99

All crabs to me are opportunists and if they can catch it they will eat it. Period.

Herbivorous crabs with spoon tipped claws cannot catch or kill fish unless there is a massive size difference. Period.

Originally Posted by Uncle99

People told me it was my fault because I should have fed them, garbage....I do not need them in my CUC because I provide perfect water consistently and have no algae for them to eat. I do keep snails, but nothing else.....18 months since...not one loss.....beware!

Or you dont overstock crabs. If you dont overstock crabs and provide them with large number of empty shells, they dont kill snails. I have been keeping same 10 hermit crabs I bought 5 years ago and I haven't bought any new snails in that 5 years

Originally Posted by Uncle99

To me, having crabs as a CUC is a myth, the amount of clean up they do is minimal, I found I could pick any small pieces by hand in 2 minutes, I spend most of my time making sure it does not develop, by regular hand maintainence, great water changed weekly, a balanced photoperiod if only 9 hours.

Same is also true for snails. No CUC, snail or crab is necessary. You can do all by hand. CUC just makes it easier. And certainly there are thing that crabs can do and snails cant.




OP, emerald crabs do not kill healthy fish. It was most likely scavenging on a already dead fish or a near death fish.

[Uncle99]

Thanks so much for your insight.
Mine is just one reefers opinion, even after more than 25 years, I certainly don't claim to be an expert. I am a reefer which does not possess your level of expertise, so I play it safe.
I am so thankful that this information was given to me a couple of years ago now as the results have been spectacular.
I simply try to provide others with alternatives, especially when new, identification and inhabitant mixes can be somewhat confusing at times, even for the experts.

I can't count the times I was told "well it worked in my reef" and "hey, that's reef safe"

My goal this time was to eliminate potential troubles and have certainly learned that what works for one does not mean it works for another...

My snails selection keeps the rocks clean and the sand stirred, glass remains my job

[top shelf]

Right, wrong, or indifferent I'm with Uncle on the no crabs. I have gone a step further and no shrimp either as I like feeding my lps from time to time and once they realize they can be a source of free food all bets are off. To OP if you fear your emerald may be the culprit you can put it in the sump or give/trade to lfs. One less variable to worry about.