A couple of years ago I left mine for a fortnight with one of those 14 day dead daphnia cake things. I think Tetra sell them.
I did massive water change day before go and another one when I came home.
I think the food block was unnecessary and potentially dangerous - but I used it anyway. I also added a cattappa leaf and some other botanics.
Back then I kept records of water testing, and the nitrate was only 20 (basically same as when i left) when i got back, the food block not touched by fish and shrimp and presumabely not by heterotroph bacteria either (extremely luckily).
Just to clear i dont suggest the holiday food - i suggest the opposite.
In my opinion a planted tank with leaves, pine alder cones, algae, etc will support your fish for up to two weeks, more for all I know. I even think my nitrate might have gone down to zero had I not added the holiday block.
As far as I know no-one starved to death, but its not impossible, and if so I would guess that is what fed the tank, but I actually think not... my 'scape was busy enough that livestock counting was only approximate; often I would count 2 more tetras on wednesday compared to tuesday for example. And I was certainly counting several more adult shrimp at end of holiday compared to start also. Plus the cories had probably had babies as they had laid eggs 2 or 3 days before holiday. So if anything the livestock increased in number.
