Ask who actually jumped from a convict cichlid tank and the answer is revealing: often it is not the convict. Convicts are confident, bottom-and-cave-oriented fish that hold territory rather than flee, but they are famously assertive, and a breeding pair will drive every other fish in the tank away from their chosen site with total commitment. The fish that leaves is the one being driven, a tankmate or a subordinate convict that has been chased up the water column, cornered at the surface, and finally pushed through the only opening left. Lids matter here, but in this tank the jumping problem is really an aggression problem wearing a lid-shaped disguise.
Breeding turns chasing into eviction
A convict pair with eggs or fry defends an expanding circle around their cave or flowerpot, and their charges are fast, repeated and aimed at whoever is nearest. Other fish learn to live at the far end and near the surface, exactly the position from which a final rush produces a jump. A single convict can do a milder version of the same thing, bullying a weaker cichlid or a slow tankmate until the victim spends its life one scare from the rim. Watch honestly for the pattern: one fish pinched into a top corner, torn fins, constant hovering by the heater.
Fit the lid, then fix the map
Start with the physical barrier regardless: a firm, full lid with the equipment cut-outs closed, because a panicked fish in this tank jumps hard and aims for corners. Then redraw the tank's map. Provide more caves and shelters than there are fish, place them at both ends, and stack rockwork, wood and plants to break sightlines so a chased fish can get out of the aggressor's view within a short dash at low level. A fish that disappears from sight is usually left alone; a fish fleeing across open water is chased to the glass. Keep the waterline slightly low as a final margin, and make sure a subordinate fish's preferred hiding corner is not directly beneath the one gap in the cover.
Manage the pair, not just the tank
When a pair spawns, decide early how the tank will absorb it. Options that genuinely work include moving the other fish out for the breeding period, moving the pair to their own tank, or dividing the aquarium so the pair's territory is physically sealed off. Rehome a surplus male if two males are fighting a war of attrition, and think carefully before adding any new fish to an established convict's tank, since newcomers take the worst of the chasing while they have no learned refuges. If the jumping fish is a convict itself, it is almost certainly the loser in such a conflict and needs separation, not just a better lid.
Keep the rest of the tank settled
Convicts dig, rearrange and test everything, so secure the lid against a fish that can move décor and splash at the surface during disputes, and keep up water quality in a tank where digging stirs waste. Test the water if the whole tank turns restless, since irritated fish quarrel more and chase harder.
After a fish goes over
Return a jumped fish promptly with wet hands and check it for damage, but do not simply put a battered subordinate back into the same corner it fled. Hold it in a separate tank or divider while you rearrange territory or move the aggressors, otherwise the next jump is scheduled. Inspect the lid gap it used and close it the same day. For escapes that get beyond the room, KinsLe's Lost Pet Alert System sends a free alert to nearby Circle of Love members, giving any missing pet a wider circle of people looking out for it.