i have 5 red minor tetras and 8 neon tetras...and i dont really think the blue gravel makes those fish pop out much. but im not sure if black would look bad.
I like the look of black gravel or sand, and have used both in several of my tanks. I would not recommend the Top Fin black gravel. I used it once in a 29 gallon, and the color ended up coming off enough that it just kinda looked gray after awhile.
have you ever see blue gravel in a stream or lake? i dont know what people are thinkin when they use anything but natural colors in a tank just my opinion
I agree that black gravel or sand will make your fish just really stand out. It's a great neutral that allows a variety of fish coloring to work better together, as well as pulling your overall decor in line, too.