Sorry I haven't seen this earlier, but my father used to have 2 fiddler crabs, and his fish started dying after a few months. He was in the dark about why -- so one day early in the morning he was just watching his tank and one of them came out of the gravel out of nowhere and attacked one of his zebra danios! so mystery explained, lol.
lol! that's weird, emppleco! although fiddler crabs don't live with fish anyways. they need dry land, so that may have been the reason for them to be acting so weird! anyways, I'm leaving to get them right now, so I'll tell you how it works! bye!
Yeah, I would imagine so! I've got them now, and they seem to be doing fine! I saw one climb a little piece of driftwood, and then the other one follow it up there . . . hehehe it was funny! The larger one (Dad) pushed Mom off! KerPLUNK!!!
I have had fiddler crabs since the start and they are totally cool. They will entertain you for hours. But make sure you tank is totally sealed closed or they will get out. I have had a few get out. They are scavangers and eat what is on the bottom of the tank. So they will help in the clean up process. I keep two at a clip and I always get males because they have the large claw. The females have two small claws. They do not mess with your fish. If a fish gets to close to them they will shake their claw but I have never had a problem with them and the fish. They will climb to the top of the waterline either on your heater or anything that will get the up and out of the water for a while. They will hang there for a while. They need to be able to come out of the water now and then. Adding salt to your tank will charm them as they are a brackish animal. You can drop some bottom pellets for them as treats every now and then. Every so often I will take one out and gently handle him. When they are in a matting mode they will shake their large claw high above them. This makes a rattling noise to get the females attention. All and all they are very cool and I hghly recommend getting at least two. You will not be disappointed. I hope this helps.