Why loaches leave tanks that hold other fish
Yoyo loaches explore for a living. By day they wedge into caves and under wood; by night they range the whole tank, nosing into filter intakes, climbing in the current, and investigating the waterline and everything beyond it. They are also startled into sudden, powerful bursts. The result is a fish that does not so much jump once as systematically test the perimeter — and their slim, flexible bodies pass through openings around pipework and cables that would never release a tetra or a barb. Most yoyo escapes happen overnight, which is why the morning headcount is the usual discovery.
Seal for a climber, not just a jumper
Fit a full lid, then close every cut-out with fine mesh or acrylic infill that is secured against pushing from below — a loach does not only fly at gaps, it presses and works at them. Run a finger along the seal around filter inlets and outlets, heater cables and airline entries, and look at the tank from water level after dark with a torch if losses have occurred: the light line you can see is the route. Keep the water level a few inches below the rim so an upward burst loses height before it reaches any remaining seam.
Pay special attention after equipment changes and deep cleans, when infill pieces are set aside and forgotten, and check inside external filter housings and the floor around the tank if a loach goes missing before assuming the worst — these fish turn up in improbable refuges, still in the water or recently out of it.
A tank that gives exploration a safe outlet
A loach with nowhere to hide is a loach looking for somewhere to be. Caves, tubes, wood and leaf litter at ground level absorb much of the investigative drive that otherwise ends at the lid, and a group of yoyos — they are social fish — spends its nights sparring and foraging among themselves rather than roaming anxiously alone. Smooth, fine substrate protects their undersides as they dig and sift. Keep the evening routine calm around the tank: lights that fade rather than snap, and no late-night tapping or netting, since a startled loach's burst is exactly the leap that finds a seam.
Restlessness at the surface, repeated climbing of the glass, or a fish spending the day in the open when it used to hide can also signal water trouble in this species, so test and check the filter if the behaviour is new, correcting drift with a partial change of matched, conditioned water.
After an escape, and the dusk check
A loach found out of the tank goes back promptly with wet hands — never by the tail — into low light, and should be watched for skin damage, since their scaleless skin suffers quickly in air and dust; damage that worsens or a fish that stops foraging needs prompt advice from an aquatic veterinarian or an experienced local fish service. Then find the exit before the next nightfall: it will be used again.
Because this tank's safety is a list of specific seams checked at a specific hour, KinsLe Family Sharing lets the loaches' shared profile carry the dusk seal-check in their details, so anyone closing up the tank for the night works from the same list.