Its objectively not. Fish may be startled by a singular, out of the norm noises, but that can happen regardless of background noise. Fish are not bothered by sustained noise, even when it’s pretty loud (by human standards). The sound of a reef is incredibly loud. Just some averages: a reef during a storm can reach over 200 decibels, an average reef during good weather can be anywhere from 75-90 decibels. The seas around Antarctica average a 100 or more. The open ocean averages over 40 decibels. Whales can sing at over 230 decibels. A reef has the sound of all the water moving and crashing against the reef, the sound of all of the fish and inverts grunting and clicking and snapping, corals breaking and rocks tumbling, the distant sounds of whales and the shore, the sound of the wind, there is just a lot of different sounds that add up to a very loud environment.
A reef does not go quite at night. And for the record, I don’t think anyone is suggesting that you should play loud music or turn your TV on full blast in the same room as your tank, the question was ‘does the sound from having a TV on bother fish?’. A TV or stereo at levels where if you lived in an apartment your neighbors wouldn’t complain isn’t going to bother your fish one bit.
