Gah! Emerald Crab is a murderer!

[fourmyclowns]

I’ve had an Emerald Crab before and never a problem, but whoa! Big shocker tonight when he was caught eating my firefish. And no, he was not “cleaning up”. Firefish was not sick, but a bit displaced by some rearranging. He has been looking for a new territory and hanging out in unusual spots. Total bummer! Are Emeralds not reef safe? Will an anemone protect my clowns from him?

[Sniperhank]

All crabs are opportunistic eaters. When it comes to emeralds, they lack the ability to do any actual hunting of a healthy fish. Something was going on to where the crab was able to take advantage to clean up the corpse, be the fish fully deceased yet or not.
Even with that said, it doesn't change if one would be 'reef safe' or not. Reef safe refers to if something will eat corals or even other invertebrates in the system. Emeralds sometimes will consume things like polyps or coral, but I would put money that something had gone on for them to develop a taste for them to begin with.
Emerald crabs won't have an established territory in our systems. They will wander around searching for their next meal, in this case your fish.
Can you tell us more about the system? How large is it, current livestock, parameters, any changes recently, and how long you had the firefish?

[fourmyclowns]

Hi Sniperhank - thank you for replying to my panicky thread. I’m calming down and thinking over your suggestion that maybe something was up with the firefish. I’m sure he was stressed with all the changes we have been making over the last two months. However, I fed them 30 minutes prior to the incident and he came out and was swimming as usual. He had been trying out different hiding spots with all the changes.

Tank is 14 years old - firefish was 2. I let the stock dwindle after the clowns died at age 13 and then let it run with 1-2 fish for 6 months.
Recent repair to protein skimmer, addition of macro algae, new LED’s this week, removal of wavebox for repair, added in poly elbows for shelter, addition of clean up crew and stock except the firefish.
Nitrate spike mid March after stocking, but currently ranging 5-20.
75 gal/10 gal sump 2 500 Gh pumps, ph8.2 all parameters 0 except nitrate 85# live rock.

Stock: Yellow tang, sailfin tang (for now), coral beauty, orchid dottyback, Ocellaris clown pair.

I’m planning on adding corals and an anemone and maybe trading out the sailfin for a sandsifter, but not if he’s going to be bait..
I welcome your thoughts!

[Sniperhank]

Two tangs and a coral beauty in a 75 is far from enough room. I’m sure there was stress and aggression going on at some level.

[fourmyclowns]

Yeah, I agree. I don’t think I’ll keep the sailfin. LFS guy assured me he was fine in a 75 and was getting along well with the yellow, but when I got home and read up on it I realized he’s going to need a new home soon. I found a link to Animal World that I can quickly check when I’m feeling impulsive instead of asking the employees at Petco.We only have two places that sell saltwater fish within 200 miles. I’m getting to know the new store owner and hoping he’ll work with me. Petco does not take returns.

[Sniperhank]

Check out liveaquaria.com. They have the best size recommendations I've come across. Good luck with your exchange.