As instructors we often get the question "I saw a yellow fish – what was it?" Answer "I dunno, haven’t a foggiest!" Colour is just one part of fish identification and please remember what happens to colour as we get deeper – think of your open water theory. As we go deeper more and more colour is lost. By 10m red has virtually disappeared. So colour has a place but its use must be tempered with common sense, besides there are many yellow fish. Ok what else can we use? Size –