Mystery Killer! - Opinions/Advise

[CookeRS]

Hi Aquarist.

I'm a bit stumped, been in hobby for a long time, almost 10 years, but I can't put my finger on these losses.

So I have an almost 1 y.o tank, and something (I'm pretty sure) is eating my inverts. I just have never seen what it is. I'm fairly sure it's not water quality, or starvation, or generic stuff, I'll elaborate why I think there's a mystery killer hiding in the shadows. I'd love any advise as to what it could be (and how I might be able to find it/trap it).

I've lost 2 peppermint shrimp, a red line cleaner shrimp (expensive here in AUS!), a hermit crab, and 2 Nassarius Snails, and a turbo snail in a 6-8month period.

1) Disappear without a trace
- when I notice my invert is missing, I will search for them, lifting rocks and peeking in as many crevasses as I can, never find remains of said invert.

2) Water Parameters in check
- standard parameters are where they should be, salinity 1.025, temp 25 (celcius), pH sits between 8 and 8.2, Ammonia and Phos always close to 0. Calcium generally a little lower on scale, high 300's usually, but corals & fish look happy.

3) Known Habitants
- to the best of my knowledge known enhabitants should be compatible.

Current known enhabitants
- 2 Small Hermit Crabs (down from 3)
- 1 Nassarius Snail (down from 3)
- 0 Peppermint Shrimp (down from 2)
- 0 Red Line Cleaner Shrimp (down from 1)
- 1 Oscelaris Clownfish
- 1 Fairy Wrasse
- 2 Firetail Goby

Known Hitchikers
- I've seen 2-3 small unidentified crabs (no bigger than the hermit crabs)
- Misc snails/worms.

Any ideas on what could be taking out my inverts would be appreciated.

(Photo of my tank attached for reference)

Cheers

 

[Retro Reefer]

Maybe a mantis shrimp? do your hear any clicking coming from your tank? You would still see empty shells from snails and hermits though.

 

[therealman1]

Could be a bobbit worm, for your sake I hope that isn't the case. When I had one It Cause me so much headache that I got out of the hobby for a year. I would get a critter trap, I know there are ones that can catch worms and crabs. Place it for a night and see what you can catch, whatever it is it clearly has an apatite.

 

[TexasTodd]

Mantis is my guess too.

 

[Retro Reefer]

Don’t think it’s a Bobbit worm, they mostly feed on small fish, other worms, detritus and some algae’s.

 

[CookeRS]

Maybe a mantis shrimp? do your hear any clicking coming from your tank? You would still see empty shells from snails and hermits though.

Sorry, when I say without a trace, only the shrimp went without a trace, the shells my snails/crab turned up empty basically.

 

[CookeRS]

I have heard some clicking, I'm just surprised I've never seen "it". Because I've gone around with a torch searching through my live rock and seen nothing...

So regarding catching a mantis shrimp, just setting up a trap at bottom of tank? I think I know how I can do this with like a soda bottle...

 

[3mm3]

Eunicid worm is my first choice.

 

[CookeRS]

Eunicid worm is my first choice.

How do you de-worm a tank [emoji14]

I'm imaging not as easy as a tablet haha.

 

[TexasTodd]

I doubt a worm with the clicking you've heard.

 

[3mm3]

I completely missed the post where you mentioned hearing clicking.

Definitely need to set out some bait at night and try to determine what you have.

 

[CookeRS]

So I've run a makeshift invert trap over the weekend... Didn't catch anything. (other than my Nassarius Snail! Haha) But I did spot this crab over the weekend... Would he be capable of taking out two peppermints?