Unidentified Crab having Babies

Frigideus · 2026-07-27T00:28:34-0400

I posted another thread trying to identify some crabs I had in my tank, and while it is still unclear to me what they are (Ive gotten quite a few different answers atp), I discovered a third one, and this one is carrying eggs. I don't have any lfs I can drop these off at, and I don't know if they will play nice with the sea hare that lives in my sump. Does anyone have any idea what I can do with the pair? She was pretty far back in the rocks so the picture is awful. Any advice is appreciated.

strich · 2026-07-27T00:36:31-0400

I'm no crab expert, but I do believe its very hard to see crab eggs reach any kind of success in a tank without a lot of effort on your part - They get eaten or sucked up in filters and skimmers. So I imagine you don't really have to worry about it.

Again, not an expert, but looks a bit like a gorilla crab and if so isn't safe around most things including the hare.

CheifReeferNB · 2026-07-27T01:54:21-0400

These are Red Mithrax crabs. You can tell by the claw shape. Same family as emeralds, mostly reef safe unless they get very hungry and they snack on corals. As far as the eggs go, it would be very unlikely to see them successfully raised in a reef tank.

kevgib67 · 2026-07-27T06:52:51-0400

Definitely red mithrax crab, I have about half a dozen in my tank with about the same number of emerald crabs. Mine have caused no problems and spend the day munching on algae all day. They are prolific eaters of bubble algae so if any get introduced to your tank there won’t be any problems. I’ve had emeralds in my tank for about four years, never have they reproduced. I think their larval stage gets eaten and/or sucked up on the filtration.

keagan · 2026-07-27T07:02:32-0400

The rounded tips on the claws show that the crab has a diet of mainly algae and biofilm. "Bad" crabs like gorilla crabs have pointed claws for catching and dismembering prey. Gorilla in particular have black tips on said claws.

If you want to OP you could raise the larval stage in a reactor setup if you can culture enough food to raise them. It's not exactly easy but it's fun to try.