That depends on how deep. There are fish that live in darkness all the time. Some don't even develop eyes, because they don't need them. But other fish have some kind of glowing light on their bodies that attract prey, so there is some light even down in the blackness.
It helps the fish see its prey in the dark ocean
The artist of the print 'Some fish live so deep in the ocean where it's dark they grow their own light' is Andrea Bowers.
It has light and it also produces its own light and thus when it is very dark it could lit up its own light and see clearly.
The zone in the open ocean where light penetrates only to a depth of a few hundred meters is called the photic zone. This layer supports photosynthesis and is home to a variety of marine life, including phytoplankton and some fish species. Beyond this zone lies the aphotic zone, where light does not reach, making it dark and often inhabited by organisms adapted to those conditions.
in a tank or the ocean?
Angler fish look like they are dark but they are grey they are very ugly and live in the antartic ocean where its very dark they can also be found in the depth in the atlantic ocean they eat shrimp snails and other smaller pray that lives in the depths of the ocean it atracts pray by its light on its head fish and shrimps think their light is smaller prey that they can eat and when they get close enough the angler fish will attack.
light fish live in the artic ocean
the dark
The bread and the cheese!
behavioral
To see and attract fish in the dark
Very dark. No light from the surface can penetrate below about 600 feet deep. The only sources of light are bio-luminescent fish, who generate faint light (like lightning bugs) that is used to attract prey.