ocean rock raises the ph, african cichlids prefer these higher phs, of about ph8. most "tropical" fish however either come from neutral backgrounds, or slightly acidic in nature, so dont require and wouldnt thrive by using ocean rock
African Cichlids require a high pH, while most Tropicals require nearly neutral pH, while South American Cichlids (New World) generally require low pH.
is there away i can get the look of ocean rock ? without the ph raising ? maybe an imitation rock or something , or any other rock that i could use in my tropical tank