Tub gurnard. Gurnards are strange-looking, bottom-feeding fish which use the three bottom rays of their pectoral fins to "feel" the sea bed. They have firm-textured white meat with not much flavour. They are rich in protein, iodine and phosphorus. The tub gurnard is a large brownish-orange variety with bright orange pectoral fins and is the one most readily available in the United Kingdom. They are all very bony fish. Small ones are excellent in soup. Red or grey mullet (US: striped mullet can generally be substituted for it, and are usually better.