A tetra sitter rarely fails on the food amount; they fail on not knowing what your school normally looks like, so they cannot tell a quiet evening from the start of a problem. Tetras are small, schooling and sensitive to change, which makes the sitter's real job simple to state: keep everything exactly the same, watch against written baselines from your own tank, and report change instead of fixing it.
Describe How the School Should Look
Walk the sitter to the tank before you leave and describe the school on an ordinary good day: fish spread through the middle water rather than packed in one corner, moving together loosely, rising calmly to food and settling again afterwards. Note that colour looks washed out first thing and brightens within about an hour after lights-on, so a sitter who arrives early should not panic at pale fish under fresh light. Point out any individual the sitter should recognise, such as the one-eyed fish or the noticeably small tetra, so an ordinary resident is not reported as a stranger or a missing fish miscounted.
Leave the Timer Times and a Hands-Off Rule
Write down the exact times your light timer switches on and off, and state plainly that the sitter should not adjust the timer, the heater dial or the filter for any reason. Tetras suffer more from well-meant tinkering than from a routine left alone: a longer light day grows algae and stresses the school, and a heater nudged by guesswork can swing temperature far faster than the fault it was meant to cure. If a light fails or equipment stops, the instruction is to phone you and follow what you say, not to experiment. Tape a small note on the timer itself if you think a helpful visitor might otherwise reset it after a power flicker.
Write Your Tank's Own Temperature Baseline
Beside the thermometer, write the temperature reading your tank usually shows, taken from your own thermometer on an ordinary day, and the small range it drifts within across a normal day. Ask the sitter to read that thermometer at each visit and compare it with your written figure rather than with any general idea of what tetra water should be. A reading close to your baseline needs no action. A reading clearly outside your written range, or a thermometer that shows nothing sensible, means phone you the same visit, because you know whether the tank runs warm in summer afternoons or whether the heater itself may have failed.
Build In the Head-Count Habit
Ask for a rough head count at every visit: stand still, let the school settle, and check the group looks its usual size against the number you have written on the instruction card. Tetras hide among plants and drift behind wood, so the habit is about spotting a clear shortfall, not achieving a perfect census of moving fish. If the school looks plainly smaller, the sitter should look along the substrate and behind the filter for a missing fish, photograph what they find, and phone you rather than reaching in to rearrange the tank. Finding and reporting a dead fish early protects the whole school, since a body left in warm water fouls it quickly.
Name the Phone-You Signs Exactly
List three signs that always mean a call the same visit: fish gasping or bunched together at the surface, water that has turned cloudy or milky, and any dead or missing fish. Add a fourth for your tank if it applies, such as water on the floor or a silent filter. For anything odd that falls outside the list, the instruction is photograph it, send the picture, and change nothing until you reply, because tetras are poor candidates for emergency products dosed by a visitor who does not know the tank. Thank the sitter for restraint in advance; doing nothing and reporting quickly is skilled care for this tank.
Before you travel, load the finished instruction card into KinsLe under Care Pass with access limited to the sitter and the trip, replacing scattered texts with one dated handover the sitter can reopen at the tank.