Missing fish
 

In the last week I've had a royal gramma and a tail spot blenny go missing. Both fish were eating great and healthy. Now today one of my cleaner shrimp is missing.

Parameters are:

Temp 78
pH 8.25
Ammonia 0
Nitrite 0
Nitrate 0
Phosphate 0 (finding hard to believe as I've had a minor cyano outbreak lately)
Cal 420
Alk 8
Mag 1210

The only thing I've done is increase the flow on my tunze's by a measily 10%, but this was after the tail spot and gramma were already MIA. Both were relatively new additions, within the last month, but they were fitting in fine.

I checked my sump and overflows as best I could.

I found one larger hermit crab that could be a suspect but I've had him since I first added my CUC and he never caused issues before.

Anyone have any ideas? I don't want anyone else to dissapear.

ETA: I highly doubt I have a mantis or something in there. The only new LR I've gotten has been placed in the sump.

royal grammas are notorious for hiding for days at a time, mine went MIA for 2 weeks then appeared out of nowhere.

I hope that's the case. It's just odd that both Tail Spot and Gramma have disapeared on the same day (5 days ago), and are nowhere to be found. They would show themselves every feeding! Maybe they've run off together in an effort to scare me.

I also do have a cat in the house so if they both decided to jump it's not unrealistic to say that the cat would have destroyed (eaten) all evidence.

What else is in the tank?

Copperband butterly
Purple tang
Midas Blenny
3 clownfish
2 (1?) Cleaner shrimp
2 Peppermint shrimp
1 fire shrimp
a few dozen hermits and snails.

Could it be the RBTA...?

Also forgot to say Salinity is 1.026 which shouldn't matter.

Though I doubt they would both jump it is absolutely possible for a cat to eat them without a trace remaining. My cat loves whole silversides lol.

i just had this happen to a week old grass wrasse. same symptoms then suddenly gone. really hope he reapears soon as an ich outbreak occured in the tank and all others have been evacuated lol. i just dont understand how a fish can dissapear/die like that. i got a lot of rock though, but ive flashlit all the crevaces with no sign. i had a cucumber dissapear too. saltwater is strange