Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male and female turn belly to belly during spawning to ensure fertilization. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea. This action is very fast...

Tony Wu / Humphead parrotfish (Bolbometopon muricatum) shoal spawning in early morning, part of mass aggregation of thousands of fish. Caroline Islands, Palau.

Alex Mustard / Dugong (Dugong dugon) male and juvenile Golden trevally (Gnathanodon speciosus) swimming over Seagrass (Halophila stipulacea) meadow. Marsa Nabaa, Marsa Alam, Egypt.

Alex Mustard / Green turtle (Chelonia mydas) resting on sea floor and two juvenile Golden trevally (Gnathanodon speciosus). Marsa El Shouna, Marsa Alam, Egypt.

Pascal Kobeh / False clown anemonefish (Amphiprion ocellaris) in a magnificent sea anemone (Heteractis magnifica), Sulu sea, Philippines

Jordi Chias / Humped rockcod (Gobionotothen gibberiformis), Antarctic Peninsula, Antarctica.

Jordi Chias / Black rockcod (Notothenia coriiceps), Antarctic Peninsula, Antarctica.

Jordi Chias / Crocodile icefish or White-blooded fish (Channichthyidae), Antarctic Peninsula, Antarctica.

Jordi Chias / Rock cod (Notothenia) Antarctic Peninsula, Antarctica.

Jordi Chias / Black rockcod (Notothenia coriiceps), Antarctic Peninsula, Antarctica.

Alex Mustard / Three Pink anemonefish (Amphiprion perideraion) living in a purple skirted magnificent sea anemone (Heteractis magnifica) on a coral reef, below a small island. Misool, Raja Ampat, West Papua, Indones...

Alex Mustard / Whale shark (Rhincodon typus) close to the camera with a golden trevally fish (Gnathanodon speciosus) and outline of another whale shark behind , in the plankton-rich green waters of La Paz bay, Baja...

Alex Mustard / Midnight snapper (Macolor macularis) shelters in a cavern on a coral reef with white soft corals (Scleronephthya sp.) and solderfish. Vavuu Atoll, Maldives. Indian Ocean

Alex Mustard / School of White collar butterflyfish (Chaetodon collare) pack together above a coral reef. North Male Atoll, Maldives. Indian Ocean

Alex Mustard / Pair of Western clown anemonefish (Amphiprion ocellaris) spawning orange eggs on the rock beneath their Magnificent sea anemone (Heteractis magnifica) home on a coral reef. This photo shows the larger...

Alex Mustard / Whitemargin stargazer (Uranoscopus sulphureus) sets an ambush in the sand at night. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Tony Wu / Fringed blenny (Chirolophis japonicus) guarding its eggs. Miyagi Prefecture, Japan.

Tony Wu / View down the throat of a male Zoarchias major eelpout (Zoarchias major) that has opened its mouth during a confrontation with another male. Yamaguchi Prefecture, Japan. Pacific Ocean.

Tony Wu / Two male Zoarchias major eelpouts (Zoarchias major) engaged in a mouth-to-mouth confrontation. Yamaguchi Prefecture, Japan, Pacific Ocean.

Tony Wu / Zoarchias major eelpouts. (Zoarchias major) The orange individual is female, the one in the hole is male. The female has approached the male, curled around him, attempting to dislodge the male from th...

Tony Wu / Zoarchias major eelpout (Zoarchias major) with her mouth wide open. Yamaguchi Prefecture, Japan, Pacific Ocean.

Alex Mustard / Forster's hawkfish (Paracirrhites forsteri) on a coral reef. Jackson Reef, Tiran, Sinai, Egypt. Strait of Tiran, Gulf of Aqaba, Egypt.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) being cleaned by a bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Almaco jack (Seriola rivoliana) uses a discarded fishing net, drifting in the open ocean as shelter. The Bahamas.

Shane Gross / Graysby fish (Cephalopholis cruentata) a type of grouper, hiding in a sponge off Eleuthera, Bahamas.

Shane Gross / Moorish idol (Zanclus cornutus) juvenile with transparent skin in the open ocean at night off Anilao, Philippines.

Shane Gross / A juvenile soldierfish, possibly a Crescent-tail bigeye (Priacanthus hamrur) in the open ocean at night off Anilao, Philippines.

Georgette Douwma / Banggai cardinalfish (Pterapogon kauderni) with a Corkscrew or Long tentacle anemone (Macrodactyla doreensis). Lembeh Strait, North Sulawesi, Indonesia.

Nick Hawkins / Atlantic salmon (Salmon salar) under river ice. Quebec, Canada. October.

Nick Hawkins / Chum salmon (Oncorhynchus keta) migrate up a small river near Bella Bella, British Columbia, Canada. September

Nick Hawkins / Blue shark (Prionace glauca) with a pair of pilot fish (Naucrates ductor) off Halifax, Nova Scotia, Canada. July.

Nick Hawkins / Atlantic bluefin tuna (Thunnus thynnus) off Antigonish, Nova Scotia, Canada. October .

John Chan / California sea lion (Zalophus californianus) feeding on a Striped bass (Morone saxatilis), Southern California, USA.

SCOTLAND: The Big Picture / Cuckoo wrasse (Labrus bergylta) and Ballan wrasse (Labrus bergylta) on the wreck of Jayne, Shetland

Franco Banfi / Freshwater fish including Cichlid between water plants and leaves. Cenote Nicte-Ha, near Tulum, Quintana Roo, Yucatan Peninsula, Mexico.

Franco Banfi / Freshwater fish including Mayan cichlids (Mayaheros urophthalmus) between aquatic plants and leaves, Cenote Nicte-Ha, near Tulum, Quintana Roo, Yucatan Peninsula, Mexico. MontPhoto Competition 2023 -...

Franco Banfi / Striped marlin (Kajikia audax) hunting Sardine (Sardinops sagax) in bait ball. Magdalena Bay, Baja California Sur, Mexico.

Duncan Murrell / Rock flagtail (Kuhlia rupestris) fish in river on the Southern Lagoon, Forgotten Coast, Lagoons of New Caledonia: Reef Diversity and Associated Ecosystems UNESCO World Heritage Site. New Caledonia.

Denis-Huot / Clownfish (Amphiprion sp) in anemone home, Philippines.

Pedro Narra / West African mudskipper (Periophthalmus barbarus) Joao Vieira Poillo , Bijagos Archipellago. Guinea Bissau

Nick Hawkins / Sergeant major (Abudefduf sp) schooling in mangroves of Isabela Island, Galapagos.

David Fleetham / Clark's anemonefish (Amphiprion clarkii), pair tending to egg mass placed beside the protection of an anemone. Yap, Micronesia.

David Fleetham / Ring-tailed cardinalfish (Ostorhinchus aureus), male protecting and incubating eggs in mouth, Philippines.

David Fleetham / Great barracuda (Sphyraena barracuda) with three parasitic Copepods at end of upper jaw. Hawaii.

Remi Masson / Pike (Esox lucius) hunting in a shoal of Perch (Perca fluviatilis), Lake Neuchatel, Switzerland. June.

Alex Mustard / Tiger cardinalfish (Cheilodipterus macrodon) male mouth brooding a clutch of eggs behind his sharp teeth. Gubal Island, Egypt. Strait Of Gubal, Red Sea.

Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male courting a female prior to spawning at dusk on a coral reef. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea.

Juergen Freund / Shoal of Sergeant majors (Abudefduf saxatilis) with various Wrasses (Labridae) feeding on the Sergeant major fish eggs, Raja Ampat, Indonesia.

Juergen Freund / Blue-lined fangblenny (Plagiotremus rhinorhynchos) hiding in a plastic container, they usually hide in deserted worm tubes or other small holes, North Sulawesi, Indonesia.

Magnus Lundgren / Wild Wonders of China / Stellar rockskipper (Entomacrodus stellifer) hiding in a barnacle. Sai Kung East Country Park, Hong Kong, China.

Remi Masson / Pair of Pumpkinseeds (Lepomis gibbosus) mating, male chasing other individuals away, River Rhone, Rhone-Alpes, France, June.

Tony Wu / Indo-Pacific sailfish (Istiophorus platypterus) in feeding frenzy, with the remains of a previously large school of sardines (Sardina sp) in background. Isla Mujeres, Cancun, Mexico.

Tony Wu / Asian sheepshead wrasse (Semicossyphus reticulatus), male in white breeding colouration. Niigata Prefecture, Honshu, Japan. June.

John Waters / Slow motion clip of a Brown trout (Salmo trutta) breaching to predate an adult Mayfly (Ephemoptera) emerged on the surface, River Kennet, Hungerford, Berkshire, England, UK, June.

John Waters / Slow motion clip of a Brown trout (Salmo trutta) predating an adult Mayfly (Ephemoptera) struggling to take off from water, River Kennet, Hungerford, Berkshire, England, UK, June.

David Fleetham / California yellowtail (Seriola lalandi dorsalis) Guadalupe Island, Mexico.

David Fleetham / Cleaner wrasse (Labroides dimidiatus) swimming alongside Golden damsel (Amblyglyphidodon aureus) looking for parasites, Fiji, Pacific Ocean.

Alex Mustard / Bengal snapper (Lutjanus bengalensis), Bannerfish (Heniochus diphreutes) and Fusiliers (Caesio sp.) diving towards coral reef to avoid predators. North Ari Atoll, Maldives. Indian Ocean.

Alex Mustard / Oriental sweetlips (Plectorhinchus vittatus) pair. South Ari Atoll, Madlives. Indian Ocean.

Alex Mustard / Striped mackerel (Rastrelliger kanagurta) shoal swimming with open mouths, filtering for zooplankton. Marsa Shouna, Port Ghalib, Marsa Alam, Egypt. Red Sea

Claudio Contreras / Black grouper (Mycteroperca bonaci) and Caribbean Reef Shark (Carcharhinus perezi), Jardines de la Reina / Gardens of the Queen National Park, Caribbean Sea, Ciego de Avila, Cuba, January

Jordi Chias / Potato cod (Epinephelus tukula) Zavora Coast, Mozambique, Indian Ocean.

Jordi Chias / Goliath grouper (Epinephelus itajara) inside a coral cave. Bloody Bay Wall, Little Cayman, Cayman Islands. British West Indies. Caribbean Sea.

Jordi Chias / Schoolmaster snapper (Lutjanus apodus) school in the reef, Little Cayman island, Cayman Islands, Caribbean.

Jordi Chias / Nassau grouper (Epinephelus striatus) on a coral reef, Little Cayman Island, Cayman Islands, Caribbean.

Jordi Chias / Blue spotted trevally (Caranx bucculentus) hunting small fish in the reef, South Ari Atoll, Maldives, Indian Ocean.

Jordi Chias / Oriental sweetlips (Plectorhinchus vittatus) South Ari Atoll, Maldives, Indian Ocean.

Jordi Chias / Red Sea anemonefish (Amphiprion bicinctus) in their home, a Sea anemone (Heteractis magnifica), on a coral reef. Big Brother island, Red Sea. Egypt.

Alex Mustard / Schools of Pacific creolefish (Cephalopholis colonus) and Panamic sergeant major (Abudefduf troschelii) swimming through sun beams inside an underwater cavern. Los Islotes, La Paz, Baja California Sur...

Franco Banfi / Three False clownfish (Amphiprion ocellaris) in Sea anemone (Heteractis magnifica) Lighthouse Reef, Cabilao Island, Bohol, Central Visayas, Philippines, Pacific Ocean.

Bert Willaert / School of Longfin spadefish (Platax teira), Kimbe Bay, West New Britain, Papua New Guinea

Nick Hawkins / Atlantic salmon (Salmo salar) migrating for spawning in river, Gaspe Peninsula, Quebec, Canada, October.

Nick Hawkins / Two Atlantic salmon (Salmo salar) silhouetted against sky, Gaspe Peninsula, Quebec, Canada, October.

Alex Mustard / Striped mackerel (Rastrelliger kanagurta) mouth wide open as it swims through the water, filtering zoopankton with its gill rakers. Marsa Shouna, Port Ghalib, Marsa Alam, Egypt. Red Sea

Michel Roggo / Atlantic salmon (Salmo salar) migrating upstream to spawn, Quebec, Canada Photographed for the Freshwater Project.

Jordi Chias / European barracuda (Sphyraena sphyraena) and Bluefish (Pomatomus saltatrix) circling baitball of Atlantic horse mackerel (Trachurus trachurus) Formigas Islets, Azores. Finalist in the Underwater Categ...

John Waters / Small group of Rainbow trout (Oncorhynchus mykiss) swimming in the River Kennet, Berkshire, England, UK, March.

John Waters / Small shoal of Brown trout (Salmo trutta) swimming and feeding in the River Kennet, Berkshire, England, UK, March.

SCOTLAND: The Big Picture / Atlantic salmon (Salmo salar) leaping up a small waterfall in order to reach breeding grounds further upstream, Cairngorms National Park, Scotland, UK, October.

Nick Upton / Common prawns (Palaemon serratus) and a Rock goby (Gobius paganellus) feeding on a dead Montagu's crab (Xantho hydrophilus) in a rockpool, Cornwall, England, UK, September.

Nick Upton / Rock goby (Gobius paganellus) stealing food from a scavenging Common prawn (Palaemon serratus) in a rockpool, Cornwall, England, UK, September.

John Waters / Pair of Brown trout (Salmo trutta) spawning, with others eating eggs, River Kennet, Berkshire, England, UK. March.

John Waters / Female Grayling (Thymallus thymallus) pursued by several males, River Kennet, Berkshire, England, UK. March.

John Waters / Pair of Brown trout (Salmo trutta) spawning, with another male trying to fertilise eggs River Kennet, Berkshire, England, UK. February.

Ann & Steve Toon / Arctic tern (Sterna paradisaea) with sandeel. Inner Farne, Northumberland, UK. July.

Alex Mustard / Ribbon sweetlips (Plectorhinchus polytaenia) USAT Liberty Wreck, Tulamben, Bali, Indonesia. Java Sea

Alex Mustard / Brandt's cormorant (Phalacrocorax penicillatus) hunts for a meal in a school of Pacific chub mackerel (Scomber japonicus) beneath an oil rig. Eureka Rig, Los Angeles, California, USA, September

Alex Mustard / Tompot blenny (Parablennius gattorugine) portrait, Swanage Pier, Swanage, Dorset, UK, English Channel, August

Jordi Chias / Two male Dusky groupers (Epinephelus marginatus) fighting for territory during mating season at 'baixa do meros', a small pinnacle at Formigas islets Protected area, near Santa Maria Island, Azores. F...

Alex Mustard / Brandt's cormorant (Phalacrocorax penicillatus) hunts for a meal in a school of Pacific chub mackerel (Scomber japonicus), beneath an oil rig. Eureka Rig, Los Angeles, California, United States of Ame...

Neil Aldridge / Nile crocodile (Crocodylus niloticus) snatching a Mozambique tilapia (Oreochromis mossambicus) in its jaws, Shingwedzi River, Kruger National Park, South Africa.

Alex Mustard / Spotlight goby (Gobiosoma louisae) looking out from inside a Yellow tube sponge (Aplysina fistularis), growing on a coral reef. Bloody Bay Wall, Little Cayman, Cayman Islands, British West Indies. Car...