Pictured in this week’s AquaNerd Picture of the Week is the rare Black Tang (Zebrasoma rostratum), seen here swimming in the large display reef at Fish Gallery’s Houston location. Before we get too far though, we have to discuss a big problem in properly identifying this fish. Most of the black tangs that come into the hobby are, in fact, not true black tangs. Instead, they are either black Scopas tangs (Z. scopas) or a presumed hybrid between a scopas and a black tang. The true black tang has jet black coloration, an elongated snout (rostrum), and a tinge or streak of green along the base of its dorsal spines. The scopas and hybrid tangs obviously don’t, but they still get that dark pigmentation which leads to all of the confusion. The particular individual shown above nearly fits the true black tang description, but it does lack the green streak prerequisite. Is this fish a hybrid? Is this just a mutant scopas tang? Our bet is on true black tang, but we don’t want to get too far ahead of ourselves. Regardless of the fish’s true identity, it’s certainly a beautiful sight you don’t see every day.