Pseudochromidae
Oblique-lined dottyback
Cypho purpurascens
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.
Oblique-lined dottyback
Apogonidae
obliquebanded cardinalfish
Apogon semiornatus
Pomacentridae
Obscure damsel
Pomacentrus adelus
Malakichthyidae
Ocean Bass
Verilus sordidus
Acanthuridae
ocean surgeonfish
Acanthurus tractus
Pomacentridae
Ocellaris clownfish
Amphiprion ocellaris
Apogonidae
Ocellate cardinalfish
Jaydia carinatus
Pomacentridae
Ocellate damselfish
Pomacentrus vaiuli
Grammistidae
Ocellate soapfish
Grammistops ocellatus
Apogonidae
ocellated cardinalfish
Apogonichthys ocellatus
Pomacentridae
Ocellated damsel
Neoglyphidodon bonang
Apogonidae
Ochre-striped cardinalfish
Ostorhinchus compressus
Serrasalmidae
Odysse's Piranha
Serrasalmus odyssei
Pempheridae
Ogasawara sweeper
Pempheris familia
Mormyridae
Ogun mormyrid
Marcusenius brucii
Cyprinidae
Oil Fish
Linichthys laticeps
Gempylidae
oilfish
Ruvettus pretiosus
Pomacentridae
Okinawa chromis
Chromis okamurai
Atherinidae
Okinawan silverside
Hypoatherina lunata
Epinephelidae
Olive grouper
Hyporthodus cifuentesi
Pomacentridae
Oman anemonefish
Amphiprion omanensis
Pempheridae
Oman sweeper
Pempheris kuriamuria
Synodontidae
Omega lizardfish
Synodus pacificus
Epinephelidae
one-blotch grouper
Epinephelus melanostigma
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.