ya thats true i just go by wut i see at my LFS hes got some tangs in 20 gallons today i went he had 3 nasos in 20 gallon long. but i asked him n he siad it doesnt matter cus ther sold in about a week. so no it makes sense. but for the goby wen i go to the store i neva see them swimming around they hang on the bottom.