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 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 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 perch
Jaydia lineata
Jaydia lineata is a little Indo-West Pacific cardinalfish with a clean set of brown vertical bands and that classic big-eyed, hang-back cardinalfish vibe. The really cool part is the breeding - the male mouthbroods the eggs, so if you ever got a pair settled in, you could actually see some neat parental care behavior.
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.
Indian sevenfinger threadfin
Filimanus similis
Filimanus similis is a small marine threadfin from the Indian Ocean with seven long, finger-like pectoral filaments it uses to feel around the bottom for food. Its color in life is usually brownish on top with a golden/silvery belly, and the fins often show darker edging, so it has that neat sandy-coast vibe. This is a demersal (bottom-associated) coastal species that shows up in trawl catches rather than the aquarium trade.
Indian spaghetti-eel
Monopterus hodgarti
This is a small swamp-eel from northeast India that lives in super shallow, muddy stream edges and will happily bury itself when it feels exposed. Its an obligate air-breather, so it will cruise up for gulps of air and can be a real escape artist if you leave gaps. Breeding behavior is neat too - the male builds/guards a nest or burrow.
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.
Inle loach
Yunnanilus brevis
This is the quirky little Inle loach from Myanmar (Lake Inle/He-Ho plain) that cruises around midwater in a loose shoal and often swims head-up (normal behavior). Unlike many loaches, it does well in calmer, well-planted setups with good water quality, and it’s best kept in groups to encourage natural schooling.
Insolitus sand eel
Yirrkala insolitus
A small tropical marine snake eel (Ophichthidae) described from New Caledonia; known from demersal habitat to about 59 m depth and reaching at least 25.8 cm TL (female). Aquarium husbandry information appears scarce because the species is rarely encountered in the trade.
Intermedia lebiasina
Lebiasina intermedia
Lebiasina intermedia is one of those super-obscure South American lebiasinids where the science side knows it, but the hobby basically never sees it. It tops out around 10.7 cm (about 4.2 inches) and, like its close relatives, its whole vibe is a slim, surface-oriented little predator that would love a tight lid and some structure up top.
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.
Iskenderun bleak
Alburnus kotschyi
Alburnus kotschyi is a freshwater bleak endemic to southern Turkey, known from the Seyhan and Ceyhan river drainages and coastal streams between Ceyhan and Arsuz (İskenderun Bay watershed). It is not a standard aquarium-trade species.
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.