Dealing with a predator in a reef

[trilinearmipmap]

If you're pretty sure it's a mantis or crab then if you don't have a lot of corals encrusted on your rock you could try dipping the rock, either a hypersalinity dip or a brief FW dip, especially if you have a good idea which rock the critter is hiding in.

I've had a clicking in the back of my tank since I set the tank up 4 or 5 years ago, never lost any fish to it and never saw any mantis. In the first year I trapped out 10 or 15 crabs but whatever is making the clicking never went into the trap.

[tang daddy]

Clicking could mean a mantis but it could also mean a pistol either way if it was a mantis you'd never fing it unless you actually saw it hiding in the rock to guess which rock would be like having a bunch of keys like 20 and 1 car.

Mantis are really smart when they hide they cut a rock and stick it snug to the entrance of their hole making you think that nothing was there.

Baby mantis can grow to a good size but would take awhile to be big.

You could try baiting the culprit with a piece of smelly prawn at night in a bottle turned on its side and a blue led shinning at the bottle sitting waiting.

Your lawn mower blenney sits on rocks so quite possible it could've gotten picked off, the mandrin was eating pods, I know you have alot of pods however a mandrin could clean shop in a month, I know my pseudo did it in 3 days. Unless the mandrin was eating brine or mysis and really fat he could have died of hunger or maybe even cyanide as 90 odd % are caught with cyanide and the rest probally speared.

If the clicks are so loud you can hear them from the other room it very well is a mantis.

[AngryTriGGer]

So I assume my best option would be to try and catch whatever may be the culprit. As far as the dragonet goes, I know it didn't decimate my pod population as i feed my tank small pellets once a day and the pods come out in huge numbers, even when the mandrin was in there. Like I said, it was fat and I had it about year. Cyanide maybe, don't know what the effects are long term..... but the clicking is there after lights out and i can hear it from other rooms in the house.

[tang daddy]

then I would bait it first I would try doing it in the rock work with a small bottle and something smelly maybe leave it overnight and check in the morning. If it's gone then repeat but only this time watching and if you get tired no problem just check again the next day. If it's gone again I would do it again and really watch. Remember mantis are smart but we are smarter always place the food in bottle the same place, once it gets familiar with the bottle it will think the bottle is food and then at that time you can try to find it's home.

Alternatively if you know forsure it's a mantis place the bottle right side up as it will take hime more time to escape, put a few rocks in the bottle and the food underneath it so it will have to fight for it's food, also tie a string to the bottle and hold onto it so you can yank it out when the bugger is in there.

[Hartjl]

I had the exact same thing in my tank; the clicking, the shrimp and fish suddenly missing, etc. I tried the bottle trap method with no luck, my mantis was just to smart. At night I could watch by the moon lights and see him approach the bottle, but he would never go into it. However, the trap did bait him out of his cave so that I could see which rock he had tunnelled into (the one on the bottom of the reef of course). His hole was covered with a perfectly shaped rock to disguise the hole. I ended up pulling the rock out of the tank in the daytime when I knew he would be in it and chipping the openning wider with a chisel. Even with the hole open I could not easily get him out and had to pry him out with a screwdriver then chase him across the floor of my fish room.
Oh yeah, watch your fingers. The way he attacked the screwdriver I'm sure glad it wasn't a finger.

[muck]

Welcome to Canreef Hartjl!!