An inexperienced aquarium hobbyist often comes home to find one or more of their fish dead on the floor, possibly caused by stress, bullying or simply lack of hiding spots within their tank. Jumping out is also a natural survival instinct among certain tropical fish; male fairy wrasses for instance may jump out if they sense they are being hunted by another tank resident and escape.
Not all fish jump due to aggression; rather, some may do so due to not enough hiding spots or hiding nooks and crannies in their tank - this could happen if it is too small, or there are too many inhabitants living within.
Poor water quality can also make fish jump. This includes dirty aquarium water, high ammonia concentrations and imbalanced pH levels, as well as tropical fish gathering near the surface for oxygen supply at its highest point; an activity which should not occur in tanks with inadequate filter systems.
An abrupt transition from light to darkness or vice versa can shock and startle fish, prompting them to startle and jump out of their tanks. Aquarium owners should aim to use lighting systems that gradually transition from dark to light in the evening and vice versa in the morning to mimic natural dusk/dawn processes found in nature.
