Small Gobies and Emerald Crabs

Rakie · Jan 21, 2019

I know this could seem off topic, but mostly my concerns are with the fish so i figured it belongs here!

So I've got bubble algae and am interested in adding an emerald crab. I'm also very nervous as I've got a few smaller 2" gobies (Tangaroa, Yasha, Neon) and I'm worried I'm going to periodically wake up to one less tiny goby.

Good or bad, please feel free to share your experience.

James M · Jan 21, 2019

IMO your okay to add them but if you are concerned. You could always provide food to the crabs like chucks of shrimp, so it won’t go after the fish as a food souce

Katrina71 · Jan 21, 2019

No way would I add a crab.

5altkreep · Jan 21, 2019

I added an emerald crab in an attempt to curb a couple of small patches of bubble algae. Hes been in there for about 6 months, and i have no complaints.
I dont see him often, but i dont see any bubble algae either. I also have a small clown goby. So far my experience has been good.

eatbreakfast · Jan 21, 2019

All crabs are opportunistic, but emeralds are probably the best behaved.

I have kept all the fish listed by the OP with them without issue.

SashimiTurtle · Jan 21, 2019

In my experience, emeralds are generally well behaved. There is a risk, but the gobies should be able to outrun the crab. Most of the time when a crab catches a fish, it is injured or dying and already on it's way to the reef tank in the sky.

I have 3 emeralds in my 90 cube and I've seen no aggression towards fish. I hardly see them at all but I know they are working as the only place bubble algae grows is on the powerheads, where they cannot reach.

jda · Jan 21, 2019

IME, emeralds are very good reef citizens when well fed. When the algae is gone, just make sure that they get something to eat and they will leave coral alone. If you just expect them to eat poop and other detritus, then expect them to much on some coral or a fish... any of us would rather than trying to live on poo. It is not hard to keep them fed... just a bit more flakes, pellets or broadcast frozen food can do fine. The emeralds from the Florida Keys are the best, IME.

Rakie · Jan 23, 2019

Awesome. Thanks all for info.

I've always been nervous about emerald crabs with a bunch of small fish around. I feed the tank heavily so he should have a LOT to scavenge.

Here's my unsolicited advice -- As someone who never had any invasive algaes until I got a zoa frag... Always remove the frag plugs. Always! The thing bit me twice, bubble algae and bryopsis. Never again lol.

AC1211 · Apr 22, 2020

Rakie said:
Awesome. Thanks all for info.

I've always been nervous about emerald crabs with a bunch of small fish around. I feed the tank heavily so he should have a LOT to scavenge.

Here's my unsolicited advice -- As someone who never had any invasive algaes until I got a zoa frag... Always remove the frag plugs. Always! The thing bit me twice, bubble algae and bryopsis. Never again lol.

If I could ask how small gobies are faring with emerald crabs for you? I have 2 emeralds already and a high fishload of 11 fish in a 60g but I want a small goby or 2 in addition to my diamond watchman and want to ensure the crabs won't take them. Any good goby suggestions I was thinking along the lines of the neon and clown gobies I debated a shrimp goby but IDK if that would work with my diamond watchman.