Established tank issue

[JohnnyRedd]

We bought an existing 180 2 years ago. About 8 months in I had fish disappearing. Tore the tank apart and found a rock crab.

About six months we added a pair of Wyoming Whites and one disappeared The smaller one.

I recently (not in the same day) added a pygmy angel, bar goby, bicolor angel. The first two disappeared. I found the bi-color this morning. Wedged into a rock with no eyes. He was actively swimming last night.

It's smaller fish that disappear. We have several larger fish (over 3 inches) but the smaller guys seem to be the target. We do have two large brittle sea stars but the bi-color was nowhere near them this morning and they are in their usual haunts with their hands out.

125 we started with all new everything... we started with a baby hippo, baby gramma and baby 6 line. All we well sized now!

I hate to start rebuilding with new rock but am starting to think the solution to pest eradication is replacing the rock structure. I have a 55 I can set up to cure rock but still...

Frustrated! Any advice/insight is appreciated.

 

[billsreef]

I'd suspect the large brittle stars and/or possibly you have a Mantis Shrimp hiding out in there. Might be worth setting up a Mantis trap for a few nights or so and see if you catch anything. Late night viewing with a red light can also be useful to see what is wandering around at night after the lights have been out for a few hours.

 

[snorvich]

A controllable fish trap baited with smelly bait will bring out the culprit. Set it just before lights out with just a small opening in the trap available for entry. Will get mantis if there.

 

[daveM100]

Trap worked great for a large teddy bear crab i had and 2 of the 4 mantis shrimp I had. If it is a mantis and the trap doesn't work, dip your rock in ro water and they come right out. Have to find them first, the last one I had hid from me for 8 months before I even knew I had one left. If all else fails, and just so everyone knows I don't like killing things, use an ice pick, works great for things that need to go but will not cooperate.

 

[hotelbravo]

are the brittle stars green? the green ones are the only real predators. on few cases a non aggressive brittle star species will attack fish but its unlikely

 

[Sk8r]

We've had great luck with a baited wine carafe, tilted up slightly on the rockwork.