“Grey snapper [fish] larvae are acoustically active during the night. … The larvae produce ‘knock’ and ‘growl’ sounds similar to the adults. … However, exactly how they produce these sounds and any other functions they may provide are still unknown.” (http://news.mongabay.com/2015/0129-montoro-fish-larvae-produce-sounds.html)
Further research is needed to confirm that the full acoustic range of these fish is in fact ‘snap, crackle, pop’.