Fish That Start With I
Browse all aquarium fish species with common names beginning with "I". Each profile includes care requirements, water parameters, tank size recommendations, and compatibility information for freshwater, marine, and brackish species.
Welcome to the letter 'I' in our species index, where you'll find a variety of fascinating aquarium fish species. Notable entries include the popular Imbellis Betta (Betta imbellis), known for its vibrant colors and peaceful nature, and the intriguing Imperial Tetra (Brachydanio rerio), prized for its schooling behavior. Although our current database has no entries under this letter, we encourage you to explore other sections for more captivating fish.
Iberian arch-mouthed nase
Iberochondrostoma lemmingii
This is a temperate Iberian river leuciscid that typically inhabits middle-to-lower river reaches with weak to moderate current and abundant aquatic vegetation. It feeds largely on algae/detritus and also zooplankton and small aquatic invertebrates. It is a native conservation-interest species in parts of its range and is not commonly encountered in the aquarium trade.
Iljin's dwarf goby
Knipowitschia iljini
This is a tiny Caspian Sea dwarf goby that sticks close to the bottom and tops out under 2 inches. The big catch is it is a deep-water, brackish/sea-influenced fish from the Caspian, so its real-world habitat needs (salinity, temperature, pressure/oxygen) make it a super uncommon aquarium candidate.
Imparfinis catfish
Imparfinis piperatus
Imparfinis piperatus is a tiny Brazilian heptapterid catfish that spends its time down on the bottom, scooting around like a little stream goblin. It stays really small (around 3.2 cm SL max), and the neat part is the subtle mottled/striped look and those long barbels that make it look way more "catfish" than its size suggests. Not super common in the aquarium trade, but it is a cool pick if you are into South American stream setups.
Indian Ocean lanternfish
Lampanyctus indicus
Lampanyctus indicus is a tiny deep-sea lanternfish from the equatorial Indian Ocean. Like other myctophids it has rows of light organs (photophores) and does the classic up-and-down daily migration in the water column. Super cool animal, but realistically its a research/deep-ocean species, not an aquarium fish.
Indian glassy fish
Parambassis ranga
This is the classic see-through "glassfish" where you can literally see the bones and organs-super cool in a planted tank with calm tankmates. They're happiest when you keep a little crew of them (they get braver and way more active in a group). Also: skip any dyed/painted ones-those fish are usually in rough shape from the process.
Indian ponyfish
Deveximentum indicium
This is a little ponyfish (slipmouth) from coastal seas and brackish edges, with that classic super-protrusible, upturned mouth they can shoot forward when they feed. Silvery body, some dark facial marking, and it tends to be a schooling, open-water kind of fish rather than a hide-in-the-rocks type.
Indonesian sawtail
Prionurus chrysurus
A Prionurus (sawtail) surgeonfish from southern Indonesia with a distinct yellow caudal fin and fixed bony plates (“sawtail”) on the caudal peduncle; described from cool upwelled seas.
Insolitus sand eel
Yirrkala insolitus
This is a little snake eel from New Caledonia that lives down in the sand and pops out like a weird underwater worm when it feels like hunting. It was described from deeper water than most of its close relatives (about 59 m), which is a big hint that it is not really an aquarium trade kind of fish. Super cool on paper, but realistically one you will almost never see for sale - and for good reason.
Iranian cichlid
Iranocichla hormuzensis
This is the wild, oddball cichlid from southern Iran that lives in warm, salty streams where most other fish would tap out. It is a maternal mouthbrooder, and adults can go dark with silvery speckling - super cool fish, but not something I'd call forgiving if your water and temps swing around.
Italian spring goby
Knipowitschia punctatissima
This is a tiny little freshwater goby from northern Italy that spends most of its time glued to the bottom, scooting between sand, gravel, and cover. In the wild it is tied to cool, clear spring-fed habitats, so it does best in an oxygen-rich tank with gentle flow and lots of little hiding spots. Its size is cute, but its needs are kind of specific, and its wild status makes it a fish I would not treat as a casual impulse buy.
Izu dragonet
Callionymus izuensis
This is a little Japanese sand-dwelling dragonet from around the Izu Islands. Think of it as a bottom-hopper that hangs out on coarse sand and rubble and spends its time picking at tiny critters like most dragonets do. Super cool fish, but it is really more of a niche, species-tank kind of project than a casual community add.