This large weedfish is commonly found on jetty pylons, where it darts in and out of algal growth. It usually has a pattern of bands and spots, and both its dorsal fins and tail have transparent windows in them to help break up their shape and look more "weedy". However, their colouration can be highly variable. They are named for their elongated snout, which is much longer than other weedfish, but are hard to distinguish otherwise. They are particularly similar to the Rosy Weedfish (Heteroclinus roseus), but apart from their snout length, H. tristis can be differentiated by its long pointed orbital tentacles and small nasal tentacles. Conversely, H. roseus has smaller leaf-shaped orbital tentacles and larger nasal tentacles with finger-shaped appendages.
