Fish and reptiles are the calmest animals to sit for and the most technically demanding, because the animal depends on equipment and the equipment can fail while you are watching something else.
What the sitter is actually responsible for
With a tank or enclosure, the sitter is maintaining an environment. Heating, lighting, filtration and humidity are keeping the animal alive, and a failure is not obvious the way a limping dog is obvious. The most useful thing an owner can leave is a short daily check routine.
- Confirm the heater or heat lamp is on and the temperature reads within the normal range. Write down what that range is.
- Confirm the filter is running and moving water.
- Confirm lighting is switching on and off as it should, or that the timer is working.
- For reptiles, check humidity where relevant and mist as directed.
- Look at the animal itself: alert, normal posture, normal colour, normal breathing.
- Note anything different, even if it seems minor.
Write the numbers down
A sitter cannot tell whether 24 degrees is correct unless you say so. Write the normal range for temperature, and for humidity where it applies, and say what to do if a reading sits outside it.
Feeding is different
Many fish and reptiles are not fed daily, and overfeeding is a much more common problem than underfeeding, particularly with fish where it also fouls the water. Give an explicit schedule with amounts, and say plainly that the animal should not be fed extra because it looks hungry.
For reptiles fed live or frozen prey, be specific about size, frequency, thawing method and handling. If this is likely to be unfamiliar or unwelcome to a sitter, raise it before they agree rather than at handover.
Plan for equipment failure and power cuts
This is the scenario worth thinking through. Leave the name and number of an aquarium or reptile shop, or the supplier who set the system up. Say where any spare heater, filter, globe or fuse is kept. Say what the sitter should do in an extended power outage, and whether there is a backup arrangement.
As with birds and small herbivores, not every vet treats reptiles or fish. Leave the name of one who does.
For sitters
Ask for a walkthrough of the equipment in person, and take a photo of the setup while it is working correctly. A photo of what normal looks like is the fastest way to spot that something has changed.
This is general information, not veterinary or aquarium advice. Follow the owner's written instructions.
