Panther Crab: Predatory?

[MrBaggy]

So I recently added a Panther Crab to my aquarium. All seemed fine. He dug himself a little cave among my driftwood, scavenged and foraged at night, ate the occasional vegetable I'd sink to the bottom.

More recently, I've been trying to add some Thai Flying Foxes to control the algae that wants so badly to grow on my plants. They worked fantastically for controlling that, until they began to disappear, about one per week.

I just a did a little experiment tonight. I turned out my aquarium lights and left the room light on, just to observe how my fish were behaving (I suspected another one of my larger fish were making a meal of them, but they generally seem uninterested in the flying foxes during the day). Lo and behold, my panther crab came out of hiding, foraged for a bit, then found a good hiding spot to watch the scenery. Every time one of my flying foxes would carelessly swim too close by, he'd try to snatch them up.

So what I'm getting at, is I think these guys are more than just scavengers. Can anyone confirm if they're actively predatory, or if my crab was just being defensive? Finding information on them is downright near impossible.

[Scubita]

I have had a panther crab for two years now. I have SEEN him eat fish that he has caught in his claw. It was actually kinda sad, he pinched my avocado puffer and ate him starting at the tail. By the time I saw it, the puffer was WAY beyond saving, but he was definitely still alive. Poor little guy.

Keep in mind though, this sort of thing didn't happen often. I've only had my crab kill 2 of my fish in two years. I have kept him with a mono sabae, knight goby, green spotted puffer, and mollies. Most of the time they all get along just fine. I've even seen fish swim right next to him and he leaves him alone.
I do have a 40 gallon tank though, so he has plenty of room. He leaves my knight goby alone and they both chill out on the bottom.

[Pufferpuggirl]

I know this is an old thread, but what people need to remember about Panther crabs is that they are nocturnal, and most fish are not. So when a fish goes down to the bottom of the tank to sleep, as most puffers do, that's when they are vulnerable. Not just to crabs, but other fish as well ... such as plecs and Chinese sucker fish. Both will suck onto a fish when it's down and can cause life threatening injuries or outright death.
So you need to think about what you mixing when you put different aquatics together.