Disappearing fish??

[LilNYCfish]

I have a 55gal FOWLR tank and in the last few weeks several friends have gone missing: 2 peppermint shrimp, 1 dartfish and today my green goby. The shrimp and dartfish disappeared without a trace, the goby was perfectly fine this morning, then I found my sally lightfoot crab eating him. I can't figure out if the fish are dying due to some rapid illness or if my invertebrates are hungry and hunting them.

There have not been any spikes in ammonia with any disappearance.

Remaining tankmanks:
yellow watchman goby + companion pistol shrimp
clown fish
3 cardinal fish
Banded coral shrimp
emerald crab
sally lightfoot crab
snails
hermit crabs

The testable water quality is as it should be
Sal 1.024
pH 8.2
0 nitrates, nitrites and ammonia
temp 80

About a month ago I added more live rock (quarantined first)
and started using a new water deionizer for water changes

Can't figure out what the problem is, are the crabs hunting my slow fish or are they getting sick without warning and dying?

Any ideas?

[ToddTT]

Saltwater Aquarium Invertebrates for Marine Reef Aquariums: Sally Lightfoot Crab

When large, it can become aggressive and catch and eat small invertebrates and fish.

[LilNYCfish]

Any special food I can add to keep the crab full and away from my fish?

[leebca]

Marine life forms eat continuously, throughout the day. There is no way for you to 'fill up' the predator to stop it from eating. So if the losses are due to a predator -- find the predator and remove it as soon as you can.

[LilNYCfish]

Looks like I'm going crabbing!

[ToddTT]

Crab Recipes - A fine collection of crab recipes. Several Crab Cake Recipes.

[LilNYCfish]