Set up the hospital tank before you move the fish
A bare, quiet hospital tank is the injured fish's best chance. Fill it with water from the home tank, or fresh dechlorinated water matched closely to it, so the move changes the fish's surroundings without changing its chemistry. Add a small filter with mature media from the main tank if you have it, a heater for species that need warmth, and one smooth shelter — a clean plant pot, a tube, or soft plants — so the fish can hide without scraping the injury.
Keep the setup deliberately plain. No gravel is needed, which makes the bottom easy to siphon and lets you see droppings, uneaten food, and the injury itself clearly. Dim the light or cover part of the tank, keep flow gentle, and place the tank somewhere quiet, away from household traffic and tapping hands. A lid matters: injured fish startle, and a startled fish can jump.
Move the fish with the least possible damage
Catch the fish slowly with a soft, fine net, or better, guide it into a submerged container and lift it out in its own water. Never lift an injured fish flapping in a net through the air if a container will work, and handle it with wet hands only if you must touch it at all. Settle it into the hospital tank, let it find the shelter, and leave it alone for the first hours rather than inspecting it repeatedly.
Note exactly what the injury looked like on day one — where it is, how large, whether edges look clean or ragged — and take a clear photo through the glass. Healing is gradual, and memory flatters or frightens; that first-day picture turns later checks into honest comparisons.
Daily care while it heals
Clean water is the main medicine you provide. Do small partial changes frequently with matched, dechlorinated water, siphoning the bare bottom each time so waste never sits under a fish resting low with a wound. Test the water regularly, because a small hospital tank with an immature filter can slip quickly, and an injured fish has no reserves for a second problem.
Feed small, reachable meals and remove what is not eaten. An injured fish may not chase food, so place it near the shelter entrance, and accept reduced appetite for the first day or so while watching that eating resumes. Observe once or twice a day at a set time: Is the fish holding itself normally? Is the injury the same size or smaller, with clean edges? Is it breathing calmly and venturing out more? Steady answers trending the right way are what healing looks like.
Knowing when isolation is not enough, and when it ends
Get prompt advice from an aquatic vet or experienced fish shop if the injury grows, develops fuzzy growth or spreading redness, if the fish stops eating beyond the first settling period, breathes rapidly, or cannot stay upright. Send your first photo alongside a current one; that pair tells an expert more than a description can.
Return the fish only when the injury has closed or clearly healed over, it is eating confidently, and it can swim strongly enough to hold its place among tankmates. Reintroduce it with the lights low, at feeding time, and watch the reunion — if the original aggressor or cause is still waiting, solve that first, or the hospital tank will be needed again.
Those daily checks hold together better on a shared list, and in KinsLe, Care Teams let you assign the hospital-tank water changes and injury checks to one helper at a time, with every completed task stamped on completion.