Why the frail fish becomes the target
Cichlids run their society on strength, and they read weakness quickly. A senior who has grown slow, thin and faded no longer holds the rank his size once guaranteed, and younger tank mates test him: a charge at feeding time, a nip at a passing fin, a slow eviction from the cave he has occupied for years. Each incident is small, but for a frail fish the costs compound — meals missed because he will not cross open water, fins that heal slowly, days spent hiding instead of resting in the open. He cannot win his status back, so the tank itself has to change around him before the testing becomes a decline.
Break the sight lines and multiply the shelters
Chasing in cichlids is mostly about line of sight: a fish that cannot be seen is not worth pursuing. Rearrange the tank so no fish can survey all of it from anywhere — tall plants, stacked rockwork and caves arranged to interrupt every long view, with shelters at both ends and in the middle rather than one prized cave everyone contests. Give your senior a specific territory in the quietest zone, ideally the spot he already favours, and furnish it properly: a cave with a single entrance he can guard by simply sitting in it, soft planting overhead, and a route from that cave to the surface and back that never crosses the tank's busiest open water.
Feed him around the bullies, not through them
Competition peaks at feeding time, so remove him from the contest entirely. Feed the main group first at the far end of the tank with food that keeps them busy at the surface, then deliver his meal directly into his shelter area with a pipette or by dropping sinking food where only he is waiting. He eats without being charged, they eat without noticing his portion, and his condition stops depending on his courage. If one particular fish has learned to shadow him at meals, feed that fish last and most generously at its own end, so staying home pays better than raiding.
Know when separation is the kind option
Some targeting is habit, and habit in a determined cichlid outlasts furniture. The signs that rearranging is not enough are plain: fins torn faster than they heal, a senior who never leaves his cave even at feeding time, visible weight loss, or chasing that resumes the moment lights come on. At that point use a divider to give him a private section of the tank with his own shelter and feeding, or move him — or the aggressor — to another setup entirely. Separation is not a failure of the plan; for a frail fish, a smaller peaceful territory is a better old age than a large tank he experiences as hostile.
Keeping the peace plan consistent
A rearranged tank drifts back unless everyone who maintains it understands why it looks the way it does. KinsLe's Care Teams records the layout, his feeding corner and the watch-list signs on his profile, so a family member doing water changes does not helpfully restack his rocks into the open plan that got him chased — and any fresh nipping gets noticed and logged against the same baseline.