Do fiddler crabs fight?

Male fiddler crab gone mad?

• Sorry to flood the question board out with my questions today, but I guess we have some very active tanks today. So, I've had this male fiddler crab for about 4 months now. He started out in a 5 gallon in my sons room, but my son decided he wanted to have a betta. My brother has been staying with us and took an interest in aquaculture, purchased a 10 gallon and turned it in a planted brackish water terrarium and took on Mr. Crabs and my son got his betta. The terrarium is an ideal setup for a fiddler crab with even built in caves in the land area formed by shells and rocks, hiding spots in the deep so on. He has been feed a great diet with lots of variety, fish food, algae wafers, dried shrimp, fresh boiled veggies, sinking fish pellets, seriously he is fed something different everyday so it's not as if he was starving. He added a molly fry in there out of my main tank which has been living happily with the crab for the past month with no problems, they even eat right next to each other. About 2-3 weeks ago he purchased a female fiddler crab to live in the tank with the male. There was no problems for the most part until yesterday. We observed the female molted, leaving her rather vulnerable. He attacked the female and removed 3 of her legs last night. We meant to separate them until she toughed up a bit, but not having the right condition tank set up and considering this happened rather late last night, we thought maybe we could do it this morning. Well, this morning he has killed her and is caring her around and eating her remains. It's my understanding that although not uncommon for males to fight, they rarely inflict death. It's even more odd that he would attack a female like that, unless not feed the proper diet, which is not the case. Is this common, I have seen people have as many as 4-5 fiddlers in this size set up with no problems. Do we just have a serial killer crab on our hands. What's the deal? Would it be a poor decision to ever add another crab mate with this maniac?

• Answer:

  Well some crabs do that because that find the other crab a threat and they feel they dont have enough space for two.. So usually if you dont have enough space for the two they will end up attacking each other.. So get a larger cage and make sure the krabs are the same size because if there not the same size the bigger one with pick a fight with the smaller one..