A shoal of tetras? A well-planted Amazon tank with a large shoal of neon tetras looks amazing. The bright neon blue and red against a green leafy background has got to be one of the best combinations in fishkeeping. It is no wonder that these are one of the most popular aquarium species. But as with all shoaling species, tetras need to be kept in a group to be happy. The larger the better (without overstocking your tank). Six individuals is usually seen as the absolute minimum in a shoal, but more is better. The effect of a large tank with a shoal of 30-40 neon or cardinal tetras is simply stunning