i know chinese superstition and feng shui has always been around, and the role fish play in feng shui, and that the asian aro has been revered for a very long time. let me clarify, not to take away from anyone's belief, what i meant was i think this became a household belief as a result of marketing, which isn't hard given the aro's legacy and resemblance to the mythical dragon.
as said the flowerhorn thing is a marketing ploy, but i bet the people paying thousands of dollars on one do believe they bring wealth and good luck, and people who don't keep fish probably don't even know about it. who knows maybe decades from now if the fish and marketing keep up, the flowerhorn thing will become a household belief too. but it'll never surpass the asian aro, that i'm sure.
this is totally unrelated, but my mom and aunt tell me not to keep an 'empty tank' at home cause its not good luck.