HCA: Hermit Crab Association

Fairly new hermit crab owner, had them for about a month or so.

A friend bought 3, 2 died, and I offered to take the remaining one since she wanted to get rid of it.

I then bought one small one, and one larger one for companions for the original, medium-sized one. All are purple pinchers.

I have an under tank heater, coconut fiber tropical substrate, water dish with sea sponge and de-chlorinated water.

I feed them a mixture of coconut flakes, general hermit crab food, and fresh fruit as a treat.

SO.

The large one is aggressive towards the medium sized one. The large one is female, I've been unable to sex the other two.

The large one pinched off one of the medium sized one's legs, so I separated them. She has never, to my knowledge, harmed the small one.

And the small one and medium one get along just fine.

I tried reintroducing them a few days later and I came home and the larger one had the medium one on its back, so I separated them again.

After a couple weeks of having them separated I tried reintroducing them again, and within an hour the big one was already being aggressive, knocked the small one with her claw but left it alone, and then went after the medium sized one again, so I moved her to the other end of the cage.

Is there anything I can do to address the aggression? I'd really rather not have to keep them in separate cages, it was expensive enough getting all the necessary stuff for the one cage (I've been keeping the big one in a smaller cage when separated, too small for her).

This could be a few things.
-the crab is lacking protein
-shell fight
-dominance display

It sounds to me like the first or second. I would keep her ISO for a few more weeks. Be sure to offer plenty of protein rich foods and extra shells along with proper conditions. Do you think she's due for a molt? If so, I would keep her in ISO until she completed that molt. I would also ditch the commercial foods. Many have harmful ingredients. Check out Kilimanjaro's Guide to Hermit Crab Nutrition. You may also want to take a look at the safe and unsafe foods lists.

Just another bit of advice: give your crabs salt water too. You can use any marine salt like Oceanic or Instant Ocean. Make sure that your dishes are deep enough for your largest crab to get water into its shell, large enough to submerge would be better. Do they have plenty of places to hide and things to climb on?

I agree with the previous posters' advice and would just make sure you're offering lots of protein (scrambled eggs are an easy and convenient way since most people already have eggs on hand and peanut butter also) and lots of extra shells. I would definitely assess your crabitat and its amount of hiding places. Make the most use of the vertical space as you can with climbing vines, driftwood, cholla logs, etc. Hope that helps and good luck!

Husker wrote:Just another bit of advice: give your crabs salt water too. You can use any marine salt like Oceanic or Instant Ocean. Make sure that your dishes are deep enough for your largest crab to get water into its shell, large enough to submerge would be better. Do they have plenty of places to hide and things to climb on?

oooh good catch, I missed that!