Diego Delso, CC BY-SA 4.0 (Wikimedia Commons)
About
A silvery-grey fish with an easily recognisable black "saddle" spot at the base of its tail. A very common and curious fish around rocks, jetties and piers - it often approaches swimmers.
Photos
European Pilchard
Sardina pilchardus
June - September
Common
Nomad Jellyfish
Rhopilema nomadica
Also known as: Nomad jellyfish
July - October
Occasional
Pillow Coral
Cladocora caespitosa
Also known as: Pillow coral, Μαξιλαράκι της θάλασσας, Cladocora
All year round, best seen in summer with clear waters
Common
Greater Amberjack
Seriola dumerili
Also known as: Τούνα (καταχρηστικά), Ricciola, Lecha
July - September (juveniles in shallow waters)
Common
Purple Sea Urchin
Paracentrotus lividus
All year round
Very Common
Common Pandora
Pagellus erythrinus
May - October
Occasional
Mediterranean Hermit Crab
Clibanarius erythropus
Also known as: Κλειτσινάρι, Παγούρι
April - October
Very Common
Common Cuttlefish
Sepia officinalis
March - May
Occasional
Peacock Wrasse
Symphodus tinca
All year round, more active May - October
Very Common
European Anchovy
Engraulis encrasicolus
June - September
Common
Mediterranean Rainbow Wrasse
Coris julis
Also known as: Γαϊτανούρι, Λεμοναριά
All year round
Very Common
Common Stingray
Dasyatis pastinaca
May - October
Rare
Two-Banded Seabream
Diplodus vulgaris
April - October
Common
Barrel Jellyfish
Rhizostoma pulmo
Also known as: Μέδουσα Βαρέλι
May - October
Common
Dusky Grouper
Epinephelus marginatus
June - September
Rare
Mediterranean Moray Eel
Muraena helena
All year round
Occasional
Giant Salp
Salpa maxima
Also known as: Πελαγικό Χορδωτό
March - August
Rare
Picarel
Spicara smaris
May - September
Common
Greater Weever
Trachinus draco
May - September
Common
Snakelocks Sea Anemone
Anemonia viridis
All year round
Very Common
Black Scorpionfish
Scorpaena porcus
Also known as: Μαύρη Σκορπίνα, Scorpaena, Black Scorpionfish
All year round. In summer they are more in shallow waters.
Very Common
Decorator Crab
Maja crispata
May - September
Occasional
Striped Red Mullet
Mullus barbatus / Mullus surmuletus
Also known as: Κουτσομούρα, Μπάρμπουνος, Μπαρμπουνάκι
May - October - that's when they are in shallow waters and you can see the small schools
Very Common
Sea Stars
Echinaster sepositus
All year round
Occasional
Flying Gurnard
Dactylopterus volitans
Also known as: Καπόνι, Χελιδόνα, Flying Gurnard
May - October, peak July-August
Common
Mediterranean Green Crab
Carcinus aestuarii
April - October
Very Common
Salema Porgy
Sarpa salpa
May - September
Common
Silver-Cheeked Toadfish
Lagocephalus sceleratus
June - October
Rare
Black Goby
Gobius niger
April - October
Common
Common Sole
Solea solea
April - November
Occasional
Brown Meagre
Sciaena umbra
June - September
Rare
Mediterranean Parrotfish
Sparisoma cretense
May - October
Occasional
White Seabream
Diplodus sargus
April - October
Common
Flathead Grey Mullet
Mugil cephalus
All year round
Very Common
Mediterranean Damselfish
Chromis chromis
Also known as: Χρωμίδα, Καλογριά, Καλογρίτσα
May - October
Very Common
Mediterranean Mussel
Mytilus galloprovincialis
All year round
Very Common
Garfish
Belone belone
May - September
Common
Sand Smelt
Atherina hepsetus
April - October
Very Common
Long-snouted Seahorse
Hippocampus guttulatus
Spring - Autumn
Rare
Bogue
Boops boops
May - October
Very Common
Gilthead Seabream
Sparus aurata
April - October
Very Common
Sea Cucumber (Holothuria tubulosa)
Holothuria tubulosa
Also known as: Θαλάσσιο Αγγούρι
Occasional
Red Scorpionfish
Scorpaena scrofa
All year round
Rare
Sand Steenbras
Lithognathus mormyrus
May - October
Very Common
Felimare picta (Regal Sea Goddess)
Felimare picta
Also known as: Regal Sea Goddess
Rare
Annular Seabream
Diplodus annularis
April - October
Very Common
Wide-eyed Flounder
Bothus podas
Also known as: Γλώσσα, Πλατύ, Wide-eyed Flounder
All year round
Very Common
European Seabass
Dicentrarchus labrax
May - November
Occasional
Mediterranean Horse Mackerel
Trachurus mediterraneus
June - October
Common
Fried Egg Jellyfish
Cotylorhiza tuberculata
Also known as: Τηγανητό Αυγό, Μεσογειακή Μέδουσα
June - October
Very Common
Common Octopus
Octopus vulgaris
Also known as: Οχταπόδι
All year round, easier during the summer months
Common
Compass Jellyfish
Chrysaora hysoscella
April - September
Occasional
Noble Pen Shell
Pinna nobilis
Rare
Bucchich's Goby
Gobius bucchichi
Also known as: Γωβιός, Bucchich's Goby, Γκιόζος
All year round, more active in summer
Very Common
Sea Hare
Aplysia fasciata
Also known as: Κρασάς, Γυμνοσάλιαγκας της Θάλασσας
May - October
Occasional
Black Seabream
Spondyliosoma cantharus
April - October
Common
Short-Snouted Seahorse
Hippocampus hippocampus
May - September
Rare