General Aquaria Discussion • Missing Mbuna Tank Boss

[Sosay]

So I've read other posts in the forums similar to this but I feel this one is unique. So A couple days ago I noticed my the water in my tank had an oily film on it . I chalked it up as maybe I had something on my hands when I was rearranging some rocks that got knocked over during a water change. Its probably worth mentioning I have extensive rock work in my tank. It makes for a ton of hiding spots. The substrate is sand . So a couple more days go by and the oily film comes back. All the meanwhile the shot caller (dominant male) of my tank is missing .He's a hybrid of Pseudotropheus Crabro and Tropheus Duboisi . He has a twin that is slightly smaller than him he always picks on so theyre never in the same place at the same time . So once I realized it was in fact the boss of the tank missing, I was even more perplexed . He was perfectly healthy last i saw him . I looked around the ground surrounding the tank , nothing . I don't have a cat or dog either . At first I thought maybe he had just made a new spot for himself . (I loves to dig inn the sand) but I did a thorough look around the tank with a super bright flashlight , nothing . So what is going on ?!
Thanks for any input

[Deeda]

The missing fish could be dead and trapped in the rocks somewhere and has been known to happen. I've had old fish hide in a cave or in rocks that died and only noticed them once they start to bloat up, decay or notice an obvious smell of dead fish. I have never noticed an oily film due to strong surface agitation.

The oily film on the water surface could be due to the food being fed but it's always possible there is a dead fish somewhere.

[DJRansome]

All true. And you would be surprised at how little can be left of a dead fish after a couple of days...between natural decomp and fish eating the remains. Even the skull seems to soften and be eaten or decompose in my tanks.

Definitely cover the tank to remove that scenario.

I also ensure the rock piles are spread out and/or easy to remove a rock or two for inspection.

This is common with catfish, especially if they are new to the tank...I've always found THEM alive if I tear down the tank to check.