Substrates can also have indirect effects on a system's health; dark-colored substrates, for example, are considered by some to be better for fish, as the fish display more colorfully by comparison, and are less likely to behave timidly. Apart from all other considerations, substrates are frequently chosen for their aesthetic qualities.
Substrates can affect a system's health indirectly; dark-colored substrates, in particular, are considered advantageous for fish due to better coloration and reduced timidity. Substrates are commonly selected based on their visual appeal.