Start with a headcount and a minute of watching
The most valuable thing a sitter does costs nothing: they count. Every fish accounted for, against the number and the little descriptions you left — the orange one with the white tail, the pair that always sit together. A fish missing from the count is either hiding, unwell or worse, and finding that out on Tuesday rather than at your return is the entire point of visits. Beyond the count, a minute of simply watching tells a sitter more than any gadget: fish cruising mid-water with fins open are fine; fish hanging at the surface, sitting on the gravel, or shimmying in place are not, and even a sitter who knows nothing about fish can report exactly that in a sentence.
Confirm the machinery with eyes and ears
Most holiday fish losses are equipment losses wearing a disguise. The sitter's round should include a deliberate pause at the filter: is water moving, is the hum the same hum, is the outflow breaking the surface as it should? Then the thermometer — not a judgement about fish keeping, just a number read aloud against the normal mark you taped beside it. Lights deserve the same treatment: on the timer's usual pattern, not burnt out or stuck on around the clock. None of this requires touching anything. It requires only that someone stood there and noticed, which is precisely the thing an automatic feeder cannot do and the reason the visit exists.
Water level, surface and the leak check
Evaporation is the slow emergency nobody feeds their way out of. Before you leave, mark the normal waterline on the glass with a strip of tape; on each visit the sitter compares the level with the mark and, if it has dropped beyond the small margin you specified, tops up only from the labelled container of treated water you prepared — never straight from the tap, never with a random jug of unknown history. While they are there: the surface should be moving and clear, not oily or still; the glass should not be suddenly green if it was clean last visit; and the cabinet, the floor around the stand and the wall behind deserve a glance and a dry hand, because a slow weeping seal found by a fingertip is a nuisance, while the same leak found a week later is a ceiling claim.
Report like a witness, not a vet
Brief your sitter to describe, not diagnose. 'One fish sitting on the bottom, the stripy one' reaches you with everything you need to decide whether to call your emergency contact, ask for a photo, or simply note it for your return; 'the fish looks sick' reaches you with nothing. A quick phone photo of the tank on each visit is worth more than a paragraph — you can read water clarity, fish posture and water level off it yourself from another continent. Agree the one rule that matters: anything that looks different from the last visit gets reported the same day, while it is still a small thing, rather than saved up as a surprise for your first evening home.
Leave the checklist where the visit happens
A sitter juggling keys, a cat, your plants and your tank will do the checks that are written down in the order they meet them and quietly skip the ones they half-remember. So the visit routine — headcount, watch, filter, temperature, waterline, leak glance, photo, message — belongs in one short list the sitter opens at the tank each time, not scattered across your last six texts. Setting that routine out on your KinsLe Care Pass keeps it attached to this tank's own details, so the sitter ticks through this visit's checks against this fish's normal numbers instead of relying on memory and good intentions.