Something hiding in the rock

[yfn20]

Hi,

Can someone tell me what this is? It hides in the rock, sometimes mess up the sands. I have never got a chance to look at it closely, because it does not come out when you are looking at it.

It will also be great if you could tell me whether it is good or bad to keep.

Thank you very much.

 

[aquanaut]

Fluff ????? resident expert

 

[Fluff]

I can't be 100% certain but it looks like a mantis shrimp. Good or bad is a matter of opinion. They can become a nuisence and may eat your snails and any other shrimp or crabs you have in the tank. Very cool critter though. Lots of people set up 10g species only tanks for them. They will eat prepared foods like raw shrimp and fish.

 

[yfn20]

Thanks for your replies.

It must have come with the live rock, which I introduced 9 months ago. None of my snails and shrimps have been eaten.

If you were me, would you keep it?

 

[Fluff]

If it were me? I would keep it. Just not in the main tank. I'd buy a cheap ten gallon set up and move that rock into it. :?

 

[MantisFreak]

It's really hard to tell what that is. It actually looks from the markings to me to be an Eriphia sebana (or the red-eyed crab from hell). The first time I saw mine, it was tiny. I didn't see it for another six months and when I finally saw it again, it was a monster. I named mine Arnold (for Arnold Schwarzzeneger).

I knew that I didn't have a mantis so I couldn't figure out my snail and crab losses. He was a bear to find because no matter how much I looked with a flashlight, I couldn't find his hiding space and he only came out at night. Since you know where yours is hiding, I think that I would get that rock into the sump pronto, get the crab out, and then replace the rock to the display tank just to be on the safe side.

http://www.geocities.com/ericdemuylder/menippid.htm

 

[yfn20]

I have just managed to look at it closely today. It is most likely to be a mantis shrimp. I guess I should remove it soon, right? What is the best way to catch it?

What should I do with it after I have caught it? I really do not wish to keep another tank here, my wife will kill me.

Just curious, how fast do they grow? and how big can they get?

 

[Fluff]

Really depends on the mantis. I don't know where your rock is from but normally, the mantis' we get in Florida rock don't get to big. And there are two types. There are smashers and spearers. Smashers are typically not a threat to fish but can be to inverts where spearers are a threat to fish. As for trapping it, there are ways. But you really need to be patient. Mantis are extremely smart. And you may have to try several days. You could try to do a fw dip to flush him out. They also sell traps that you can bait. You can probably find one at your local lfs. Or check online. It's called the X-terminator.
Once you do catch him though, perhaps your wife will convert. They are extremely cool critters. Your lfs may take it. Lots of people keep them.

 

[yfn20]

Definitely a mantis shrimp. Green-ish colour. It's about one inch long. Is that big?

 

[Fluff]

No, that's a small one. Were you able to capture it? Some are really beautiful. Here are some pics.

http://www.blueboard.com/mantis/pics1.htm

 

[yfn20]

Still haven't tried to capture it yet, I only saw it when it zoomed from one rock to another. It looks more like the one on Eric Cheng's picture.

I'm going on holiday in a few days time, only for a few days. I shall try to catch it when I come back.

When you say it is a small one, does that mean it is not big enough to attack my fishes and inverts yet? I have four snails, why doesn't it attack them (easy target) for the past 9 months?

 

[Fluff]

Could be he's eating hitchhikers you aren't aware of. I don't know. He might be helping relieve you of the nuisance snails and crabs. I would say at an inch, he's to small to be a threat to your fish.

 

[yfn20]

Do you think it is wise to keep it in there a few more months? It is quite interesting to see something moving around under the rocks.

Actually, I just remembered. I actually introduce two lobsters into the tank a month ago, and one of them disapeared after two days. I guess the mantis shrimp must have had a very nice dinner that day.

 

[Fluff]

No doubt he had a field day with the lobsters. Honestly, I had a 4" mantis in my tank and didn't know it for two years. He never bothered my fish. I just could never keep peppermint shrimp and snails but didn't know why. Between him and a rouge snail eating crab. Well, I ended up killing the bugger trying to remove it. If you find it's den, and keep it fed, it shouldn't be a problem for a while. When I found mine, I fed him pieces of raw shrimp for a while til I decided to set up another tank. It was trained to take food from a feeding rod. I'd like to have another someday, set up in a species only tank.
But, it might be easier to catch while small.

 

[Jermz79]

How would a Mantis do in a Nano with just some corals? I probably wouldn't want to I was just thinking it would be cool!

 

[Fluff]

As far as I know, they are not a threat to corals.

 

[MantisFreak]

The most common green hitchhiker is a Wennerae http://www.blueboard.com/mantis/pics/isaari_hammers.htm
If that is indeed what you have, their maximum size is around 2 1/2 inches. Mantis are smart. They will eat what takes the least amount of effort. I have kept Wennerae with fish and coral in a nano for years. Fish are not their preferred food source and unless it's starving and you had something like a scooter blenny that slept in the sand at night, you are probably fine. However, I still don't recommend it because I don't want you lose a $20 fish and blaming me.

They are quite safe with corals. Even shrimp and snails if it is well fed. However, you occassionally want to make it hungry enough to take out the occassional snail or crab. If they don't use their raptorial appendages enough, they can lose them in a molt like this picture. http://www.blueboard.com/mantis/pics/gawura_backside.htm (BTW...even if they have lost their "hammers", this is still not a good practice with the larger species.

 

[elke]

sumps are a nice place for the odd balls had a mantis put in my sump with a big florida stone crab a.k.a crabzilla thought i'd keep them both but the crab won