Pomacanthidae
Twospined angelfish
Centropyge bispinosa
FISH SPECIES
Flat-bodied Fish
Compare fish with laterally compressed, dorsoventrally depressed or asymmetrical body plans across habitats.
FISH ATLAS / FIELD GUIDEFlat FishIN THIS CHAPTER01 / Characteristics02 / Lifestyle03 / Species04 / Field notes
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01 / NATURAL HISTORY
Characteristics
Flattened body forms represent two distinct evolutionary paths: laterally compressed forms engineered for agility in narrow vertical spaces, and dorsoventrally depressed or asymmetrical forms specialized for living flush against the ocean floor.
- 01Laterally compressed maneuvering
- 02Dorsoventrally flattened resting
- 03Benthic sediment concealment
02 / LIFESTYLE
Lifestyle
Laterally compressed fishes like butterflyfishes and batfishes orient vertically to dart through intricate reef branches, using broad median fins to execute instantaneous, low-radius pivot turns. In stark contrast, depressed rays and asymmetrical flatfishes bury beneath sediment with only elevated eyes exposed, remaining completely motionless until striking passing prey from underneath.
OBSERVATION INDEX
- Zero-radius turns in structural cover
- Sediment concealment with raised eyes
- Undulatory pectoral propulsion on bottoms
03 / SPECIES
Representative species
Discover representative species illustrating the ecological diversity, morphologies and adaptations of this group.
Twospined angelfish
Chaetodontidae
Twospot coralfish
Coradion melanopus
Gobiidae
twospot dwarfgoby
Eviota distigma
Cirrhitidae
Twospot hawkfish
Amblycirrhitus bimacula
Labridae
twospot hogfish
Bodianus bimaculatus
Labridae
twospot wrasse
Oxycheilinus bimaculatus
Labridae
Twotone wrasse
Halichoeres prosopeion
Gobiidae
Unicolor coralgoby
Gobiodon unicolor
Pomacentridae
Unipa chromis
Chromis unipa
Gobiidae
Unpolished dwarfgoby
Eviota irrasa
Mormyridae
Upper Zambezi Bulldog
Marcusenius altisambesi
Gobiidae
Upside-down goby
Bryaninops nexus
Ophidiidae
upsilon cusk-eel
Lepophidium pheromystax
Clupeidae
Uruguay river sprat
Ramnogaster melanostoma
Melanotaeniidae
Utchee rainbowfish
Melanotaenia utcheensis
Chaetodontidae
vagabond butterflyfish
Chaetodon vagabundus
Nemacheilidae
Van loach
Oxynoemacheilus ercisianus
Pomacentridae
Vanderbilt's chromis
Pycnochromis vanderbilti
Caesionidae
variable-lined fusilier
Caesio varilineata
Mullidae
Varied-spine goatfish
Upeneus heterospinus
Apogonidae
variegated cardinalfish
Fowleria variegata
Siganidae
Variegated spinefoot
Siganus randalli
Cyprinidae
Verlorenvlei redfin
Pseudobarbus verloreni
Pomacanthidae
Vermiculated angelfish
Chaetodontoplus mesoleucus
04 / FIELD NOTES
A closer look
What is the evolutionary difference between a ray and a flounder?
A ray is a cartilaginous fish flattened from top to bottom (dorsoventrally depressed) with eyes on top and gill slits on the underside; a flounder is a bony fish that lies on its side, whose eye migrates during larval development to make the body asymmetrical.
Why do disk-shaped fish like angelfish and discus have tall bodies?
A laterally compressed disc shape provides high vertical stability and exceptional turning agility, allowing fish to twist into narrow vertical crevices and maneuver between tangled roots or coral branches without losing control.