The cool catfish in the warm tank
Panda corydoras, named for the black eye patches and tail blotch on a cream body, come from tributaries in Peru fed by cooler upland water. Their home range of about 71 to 77 degrees Fahrenheit and pH roughly 6.0 to 7.4 reflects that origin, and it sits noticeably lower than the 78-to-82-degree water many community tanks are heated to. Pandas survive warmer water — that is the trap. They survive it for a noticeably shorter span, breathing faster, feeding less eagerly, and fading a little more each month.
If you keep pandas, let them set the thermostat. Most classic community companions — small tetras, rasboras, honey gouramis — are content in the mid-seventies, so a tank at 74 or 75 degrees serves everyone. The species that truly need 80-plus degrees are the ones to rehome or house separately, not the pandas to cook slowly.
pH and the bottom they live in
Pandas spend their lives with their bellies and barbels on the substrate, so their experience of the water is the bottom layer's, where waste settles and chemistry can differ from the bright surface water a test sample usually comes from. A pH inside 6.0 to 7.4 drawn from mid-water is reassuring, but the pandas' real conditions are set by what rots beneath them. Fine sand, vacuumed gently and often, keeps the bottom layer as clean as the readings claim.
Barbels are the tell. A panda group on good substrate in suitable water wears long, intact whiskers and sifts sand constantly. Eroded barbels and a group that sits still on the bottom point to dirty substrate or abrasive gravel far more often than to the pH number itself — though persistently alkaline, hard water does wear them down, and pandas in such tanks rarely thrive even on sand.
Groups, oxygen, and the warm-water squeeze
Pandas are social to their core and should be kept in groups — six is a sensible floor, and more is better — because a lone panda is a stressed panda regardless of chemistry. Groups also make temperature stress visible: in water that has crept too warm, the whole group makes repeated dashes to the surface to gulp air.
Surface movement and a filter that ripples the top layer buy margin on warm days. During a heatwave, a panda tank near the top of its range deserves the fan-across-the-surface trick before the tetras in a hotter tank do, because the pandas run out of headroom first.
Feeding at the temperature you chose
Cooler water slows panda metabolism, so feeding should match the temperature you actually keep. At 73 degrees a group needs modest sinking food once a day, with leftovers removed; the same ration at 77 disappears faster and can be split in two. Watch bellies rather than the clock — pandas should look rounded but not swollen, and food still sitting on the sand an hour later is a message about both quantity and temperature.
Young pandas grow slowly in cool water, which is natural for the species and no reason to warm the tank. Growth bought with heat is paid for in lifespan, the worst trade in fishkeeping.
A ceiling worth writing down
The panda's key number is a maximum, and maximums are exactly what get violated by accident — a new heater set by feel, a tankmate added whose needs nobody checked against the pandas'. Recording the 77-degree ceiling, the near-neutral pH band, and the group size in writing gives the smallest fish in the tank a voice in decisions made above it. KinsLe Family Sharing puts that ceiling in the pandas' profile for everyone who shares their care, so the heater stays where the catfish need it.